231624721 has 2 divisors, whose sum is σ = 231624722. Its totient is φ = 231624720.

The previous prime is 231624707. The next prime is 231624727. The reversal of 231624721 is 127426132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126787600 + 104837121 = 11260^2 + 10239^2 .

It is a cyclic number.

It is not a de Polignac number, because 231624721 - 2⁵ = 231624689 is a prime.

It is a super-2 number, since 2×231624721² = 107300022756655682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 231624721.

It is not a weakly prime, because it can be changed into another prime (231624727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115812360 + 115812361.

It is an arithmetic number, because the mean of its divisors is an integer number (115812361).

Almost surely, 2^231624721 is an apocalyptic number.

It is an amenable number.

231624721 is a deficient number, since it is larger than the sum of its proper divisors (1).

231624721 is an equidigital number, since it uses as much as digits as its factorization.

231624721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 28.

The square root of 231624721 is about 15219.2220891871. Note that the first 3 decimals coincide. The cubic root of 231624721 is about 614.1318713949.

The spelling of 231624721 in words is "two hundred thirty-one million, six hundred twenty-four thousand, seven hundred twenty-one".