23991557 has 2 divisors, whose sum is σ = 23991558. Its totient is φ = 23991556.

The previous prime is 23991493. The next prime is 23991559. The reversal of 23991557 is 75519932.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16760836 + 7230721 = 4094^2 + 2689^2 .

It is a cyclic number.

It is not a de Polignac number, because 23991557 - 2⁶ = 23991493 is a prime.

Together with 23991559, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23991559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11995778 + 11995779.

It is an arithmetic number, because the mean of its divisors is an integer number (11995779).

Almost surely, 2^23991557 is an apocalyptic number.

It is an amenable number.

23991557 is a deficient number, since it is larger than the sum of its proper divisors (1).

23991557 is an equidigital number, since it uses as much as digits as its factorization.

23991557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 85050, while the sum is 41.

The square root of 23991557 is about 4898.1176996883. The cubic root of 23991557 is about 288.4160853356.

The spelling of 23991557 in words is "twenty-three million, nine hundred ninety-one thousand, five hundred fifty-seven".