656991618 has 16 divisors (see below), whose sum is σ = 1356370176. Its totient is φ = 211932720.

The previous prime is 656991589. The next prime is 656991623. The reversal of 656991618 is 816199656.

It is a super-2 number, since 2×656991618² = 863275972244515848, which contains 22 as substring.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 1765921 + ... + 1766292.

It is an arithmetic number, because the mean of its divisors is an integer number (84773136).

Almost surely, 2^656991618 is an apocalyptic number.

656991618 is an abundant number, since it is smaller than the sum of its proper divisors (699378558).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

656991618 is a wasteful number, since it uses less digits than its factorization.

656991618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3532249.

The product of its digits is 699840, while the sum is 51.

The square root of 656991618 is about 25631.8477289485. The cubic root of 656991618 is about 869.3338883279. Note that the first 3 decimals are identical.

The spelling of 656991618 in words is "six hundred fifty-six million, nine hundred ninety-one thousand, six hundred eighteen".