181 (number)
| ||||
|---|---|---|---|---|
| Cardinal | one hundred eighty-one | |||
| Ordinal | 181st (one hundred eighty-first) | |||
| Factorization | prime | |||
| Divisors | 1, 181 | |||
| Greek numeral | ΡΠΑ´ | |||
| Roman numeral | CLXXXI | |||
| Binary | 101101012 | |||
| Ternary | 202013 | |||
| Quaternary | 23114 | |||
| Quinary | 12115 | |||
| Senary | 5016 | |||
| Octal | 2658 | |||
| Duodecimal | 13112 | |||
| Hexadecimal | B516 | |||
| Vigesimal | 9120 | |||
| Base 36 | 5136 | |||
In mathematics
- 181 is an odd number.
- It is a prime number, which means it can only be divided evenly by 1 and itself. It's the 42nd prime.
- 181 is a palindromic number, because it reads the same forward and backward.
- It is also a twin prime with 179 (two prime numbers that differ by 2).
- As a centered polygonal number, 181 is:
- a centered square number,
- a centered pentagonal number,
- a centered 18-gonal number, and
- a centered 30-gonal number.
In science
- 181 is the atomic mass of the most common isotope of tantalum (Ta).
Fun fact
- 181 is a prime number that is also palindromic. This makes it part of a special group of numbers known as palindromic primes.
References
- 1 2 3 4 5 6 7 8 Vanovschi, Vitalii. "Properties of the number 181". www.numberempire.com. Archived from the original on 2025-10-03. Retrieved 2026-08-23.
- ↑ Sloane, N. J. A. (ed.). "Sequence A069131 (Centered 18-gonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ Sloane, N. J. A. (ed.). "Sequence A389799 (Centered 30-gonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ↑ "Tantalum-181 - isotopic data and properties". www.chemlin.org. Retrieved 2026-09-09.
- ↑ Sloane, N. J. A. (ed.). "Sequence A002385 (Palindromic primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
