21420634928 has 80 divisors (see below), whose sum is σ = 51867513600. Its totient is φ = 8325676800.

The previous prime is 21420634909. The next prime is 21420634973. The reversal of 21420634928 is 82943602412.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 498023 + ... + 539321.

It is an arithmetic number, because the mean of its divisors is an integer number (648343920).

Almost surely, 2^21420634928 is an apocalyptic number.

21420634928 is a gapful number since it is divisible by the number (28) 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 21420634928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25933756800).

21420634928 is an abundant number, since it is smaller than the sum of its proper divisors (30446878672).

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

21420634928 is a wasteful number, since it uses less digits than its factorization.

21420634928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41746 (or 41740 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 41.

The spelling of 21420634928 in words is "twenty-one billion, four hundred twenty million, six hundred thirty-four thousand, nine hundred twenty-eight".