21391074432 has 512 divisors, whose sum is σ = 82293926400. Its totient is φ = 5308416000.

The previous prime is 21391074427. The next prime is 21391074433. The reversal of 21391074432 is 23447019312.

It is a happy number.

21391074432 is a `hidden beast` number, since 213 + 9 + 1 + 0 + 7 + 4 + 432 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21391074433) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5344432 + ... + 5348432.

It is an arithmetic number, because the mean of its divisors is an integer number (160730325).

Almost surely, 2^21391074432 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 21391074432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41146963200).

21391074432 is an abundant number, since it is smaller than the sum of its proper divisors (60902851968).

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

21391074432 is a wasteful number, since it uses less digits than its factorization.

21391074432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4061 (or 4043 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The spelling of 21391074432 in words is "twenty-one billion, three hundred ninety-one million, seventy-four thousand, four hundred thirty-two".