231216961 has 2 divisors, whose sum is σ = 231216962. Its totient is φ = 231216960.

The previous prime is 231216919. The next prime is 231216991. The reversal of 231216961 is 169612132.

231216961 = T₁₂₄₁₄ + T₁₂₄₁₅ + T₁₂₄₁₆.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 223681936 + 7535025 = 14956^2 + 2745^2 .

It is a cyclic number.

It is not a de Polignac number, because 231216961 - 2¹⁵ = 231184193 is a prime.

It is a super-2 number, since 2×231216961² = 106922566108151042, which contains 22 as substring.

It is equal to p_12705844 and since 231216961 and 12705844 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (231216991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115608480 + 115608481.

It is an arithmetic number, because the mean of its divisors is an integer number (115608481).

Almost surely, 2^231216961 is an apocalyptic number.

231216961 is the 12416-th centered triangular number.

It is an amenable number.

231216961 is a deficient number, since it is larger than the sum of its proper divisors (1).

231216961 is an equidigital number, since it uses as much as digits as its factorization.

231216961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 31.

The square root of 231216961 is about 15205.8199713136. The cubic root of 231216961 is about 613.7712802009.

The spelling of 231216961 in words is "two hundred thirty-one million, two hundred sixteen thousand, nine hundred sixty-one".