21397630464 has 480 divisors, whose sum is σ = 76130841600. Its totient is φ = 5910589440.

The previous prime is 21397630439. The next prime is 21397630511. The reversal of 21397630464 is 46403679312.

21397630464 is a `hidden beast` number, since 2 + 1 + 3 + 9 + 7 + 630 + 4 + 6 + 4 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20998147 + ... + 20999165.

It is an arithmetic number, because the mean of its divisors is an integer number (158605920).

Almost surely, 2^21397630464 is an apocalyptic number.

21397630464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21397630464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38065420800).

21397630464 is an abundant number, since it is smaller than the sum of its proper divisors (54733211136).

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

21397630464 is a wasteful number, since it uses less digits than its factorization.

21397630464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1091 (or 1062 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 45.

The spelling of 21397630464 in words is "twenty-one billion, three hundred ninety-seven million, six hundred thirty thousand, four hundred sixty-four".