656821968 has 80 divisors (see below), whose sum is σ = 1896253632. Its totient is φ = 194176000.

The previous prime is 656821967. The next prime is 656821969. The reversal of 656821968 is 869128656.

It is an interprime number because it is at equal distance from previous prime (656821967) and next prime (656821969).

It is a self number, because there is not a number n which added to its sum of digits gives 656821968.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656821967) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6478 + ... + 36818.

Almost surely, 2^656821968 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 656821968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (948126816).

656821968 is an abundant number, since it is smaller than the sum of its proper divisors (1239431664).

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

656821968 is a wasteful number, since it uses less digits than its factorization.

656821968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30404 (or 30398 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 51.

The square root of 656821968 is about 25628.5381557357. The cubic root of 656821968 is about 869.2590547043.

The spelling of 656821968 in words is "six hundred fifty-six million, eight hundred twenty-one thousand, nine hundred sixty-eight".