21551200720 has 80 divisors (see below), whose sum is σ = 57283083648. Its totient is φ = 7386600960.

The previous prime is 21551200717. The next prime is 21551200733. The reversal of 21551200720 is 2700215512.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 3430222 + ... + 3436498.

Almost surely, 2^21551200720 is an apocalyptic number.

21551200720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21551200720 is an abundant number, since it is smaller than the sum of its proper divisors (35731882928).

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

21551200720 is a wasteful number, since it uses less digits than its factorization.

21551200720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12428 (or 12422 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 25.

The spelling of 21551200720 in words is "twenty-one billion, five hundred fifty-one million, two hundred thousand, seven hundred twenty".