21281525928 has 768 divisors, whose sum is σ = 73969459200. Its totient is φ = 5665904640.

The previous prime is 21281525899. The next prime is 21281525953. The reversal of 21281525928 is 82952518212.

21281525928 is a `hidden beast` number, since 2 + 1 + 2 + 8 + 1 + 52 + 592 + 8 = 666.

It is a super-2 number, since 2×21281525928² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 452798401 + ... + 452798447.

It is an arithmetic number, because the mean of its divisors is an integer number (96314400).

Almost surely, 2^21281525928 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 21281525928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36984729600).

21281525928 is an abundant number, since it is smaller than the sum of its proper divisors (52687933272).

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

21281525928 is a wasteful number, since it uses less digits than its factorization.

21281525928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 148 counting only the distinct ones).

The product of its digits is 230400, while the sum is 45.

The spelling of 21281525928 in words is "twenty-one billion, two hundred eighty-one million, five hundred twenty-five thousand, nine hundred twenty-eight".