21521019996 has 72 divisors (see below), whose sum is σ = 62752959360. Its totient is φ = 6091389216.

The previous prime is 21521019977. The next prime is 21521020013. The reversal of 21521019996 is 69991012512.

21521019996 is a `hidden beast` number, since 21 + 521 + 0 + 19 + 9 + 96 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 372106 + ... + 426033.

It is an arithmetic number, because the mean of its divisors is an integer number (871568880).

Almost surely, 2^21521019996 is an apocalyptic number.

It is an amenable number.

21521019996 is an abundant number, since it is smaller than the sum of its proper divisors (41231939364).

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

21521019996 is a wasteful number, since it uses less digits than its factorization.

21521019996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 798263 (or 798258 counting only the distinct ones).

The product of its (nonzero) digits is 87480, while the sum is 45.

The spelling of 21521019996 in words is "twenty-one billion, five hundred twenty-one million, nineteen thousand, nine hundred ninety-six".