621391638812 has 24 divisors (see below), whose sum is σ = 1243027198560. Its totient is φ = 266258433600.

The previous prime is 621391638811. The next prime is 621391638817. The reversal of 621391638812 is 218836193126.

It is a happy number.

621391638812 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×621391638812² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621391638811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2032487 + ... + 2318142.

It is an arithmetic number, because the mean of its divisors is an integer number (51792799940).

Almost surely, 2^621391638812 is an apocalyptic number.

It is an amenable number.

621391638812 is an abundant number, since it is smaller than the sum of its proper divisors (621635559748).

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

621391638812 is a wasteful number, since it uses less digits than its factorization.

621391638812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4355741 (or 4355739 counting only the distinct ones).

The product of its digits is 746496, while the sum is 50.

The spelling of 621391638812 in words is "six hundred twenty-one billion, three hundred ninety-one million, six hundred thirty-eight thousand, eight hundred twelve".