656601021 has 12 divisors (see below), whose sum is σ = 949047840. Its totient is φ = 437445960.

The previous prime is 656600999. The next prime is 656601037. The reversal of 656601021 is 120106656.

It is a happy number.

656601021 is a `hidden beast` number, since 6 + 56 + 601 + 0 + 2 + 1 = 666.

It is not a de Polignac number, because 656601021 - 2⁶ = 656600957 is a prime.

It is a super-2 number, since 2×656601021² = 862249801556484882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656601041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9081 + ... + 37358.

It is an arithmetic number, because the mean of its divisors is an integer number (79087320).

Almost surely, 2^656601021 is an apocalyptic number.

It is an amenable number.

656601021 is a deficient number, since it is larger than the sum of its proper divisors (292446819).

656601021 is a wasteful number, since it uses less digits than its factorization.

656601021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48016 (or 48013 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 656601021 is about 25624.2272273721. The cubic root of 656601021 is about 869.1615743472.

Adding to 656601021 its reverse (120106656), we get a palindrome (776707677).

The spelling of 656601021 in words is "six hundred fifty-six million, six hundred one thousand, twenty-one".