621991856 has 20 divisors (see below), whose sum is σ = 1216375272. Its totient is φ = 308088576.

The previous prime is 621991849. The next prime is 621991907. The reversal of 621991856 is 658199126.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 621991856.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 179945 + ... + 183368.

Almost surely, 2^621991856 is an apocalyptic number.

It is an amenable number.

621991856 is a deficient number, since it is larger than the sum of its proper divisors (594383416).

621991856 is a wasteful number, since it uses less digits than its factorization.

621991856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363428 (or 363422 counting only the distinct ones).

The product of its digits is 233280, while the sum is 47.

The square root of 621991856 is about 24939.7645538205. The cubic root of 621991856 is about 853.6140723970.

The spelling of 621991856 in words is "six hundred twenty-one million, nine hundred ninety-one thousand, eight hundred fifty-six".