656334021 has 16 divisors (see below), whose sum is σ = 1013830784. Its totient is φ = 369909504.

The previous prime is 656334013. The next prime is 656334023. The reversal of 656334021 is 120433656.

It is not a de Polignac number, because 656334021 - 2³ = 656334013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 656334021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656334023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 212536 + ... + 215601.

It is an arithmetic number, because the mean of its divisors is an integer number (63364424).

Almost surely, 2^656334021 is an apocalyptic number.

It is an amenable number.

656334021 is a deficient number, since it is larger than the sum of its proper divisors (357496763).

656334021 is a wasteful number, since it uses less digits than its factorization.

656334021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 428220.

The product of its (nonzero) digits is 12960, while the sum is 30.

The square root of 656334021 is about 25619.0167844123. The cubic root of 656334021 is about 869.0437465259.

Adding to 656334021 its reverse (120433656), we get a palindrome (776767677).

The spelling of 656334021 in words is "six hundred fifty-six million, three hundred thirty-four thousand, twenty-one".