15665491 has 2 divisors, whose sum is σ = 15665492. Its totient is φ = 15665490.

The previous prime is 15665473. The next prime is 15665521. The reversal of 15665491 is 19456651.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 15665491 - 2¹⁵ = 15632723 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 15665491.

It is not a weakly prime, because it can be changed into another prime (15665401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7832745 + 7832746.

It is an arithmetic number, because the mean of its divisors is an integer number (7832746).

Almost surely, 2^15665491 is an apocalyptic number.

15665491 is a deficient number, since it is larger than the sum of its proper divisors (1).

15665491 is an equidigital number, since it uses as much as digits as its factorization.

15665491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 37.

The square root of 15665491 is about 3957.9655127350. The cubic root of 15665491 is about 250.2157657270.

The spelling of 15665491 in words is "fifteen million, six hundred sixty-five thousand, four hundred ninety-one".