231658991 has 2 divisors, whose sum is σ = 231658992. Its totient is φ = 231658990.

The previous prime is 231658981. The next prime is 231659009. The reversal of 231658991 is 199856132.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 231658991 - 2¹⁰ = 231657967 is a prime.

It is a super-2 number, since 2×231658991² = 107331776222276162, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231658951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115829495 + 115829496.

It is an arithmetic number, because the mean of its divisors is an integer number (115829496).

Almost surely, 2^231658991 is an apocalyptic number.

231658991 is a deficient number, since it is larger than the sum of its proper divisors (1).

231658991 is an equidigital number, since it uses as much as digits as its factorization.

231658991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 44.

The square root of 231658991 is about 15220.3479263780. The cubic root of 231658991 is about 614.1621578302.

The spelling of 231658991 in words is "two hundred thirty-one million, six hundred fifty-eight thousand, nine hundred ninety-one".