21551402500 has 60 divisors (see below), whose sum is σ = 49177808064. Its totient is φ = 8245732000.

The previous prime is 21551402491. The next prime is 21551402527. The reversal of 21551402500 is 520415512.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 129904 + ... + 244903.

Almost surely, 2^21551402500 is an apocalyptic number.

21551402500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21551402500 is an abundant number, since it is smaller than the sum of its proper divisors (27626405564).

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

21551402500 is a wasteful number, since it uses less digits than its factorization.

21551402500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 374854 (or 374837 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The spelling of 21551402500 in words is "twenty-one billion, five hundred fifty-one million, four hundred two thousand, five hundred".