21115672720 has 40 divisors (see below), whose sum is σ = 49100857344. Its totient is φ = 8445078912.

The previous prime is 21115672717. The next prime is 21115672729. The reversal of 21115672720 is 2727651112.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21115672729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 749937 + ... + 777583.

Almost surely, 2^21115672720 is an apocalyptic number.

21115672720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21115672720 is an abundant number, since it is smaller than the sum of its proper divisors (27985184624).

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

21115672720 is a wasteful number, since it uses less digits than its factorization.

21115672720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37207 (or 37201 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 34.

The spelling of 21115672720 in words is "twenty-one billion, one hundred fifteen million, six hundred seventy-two thousand, seven hundred twenty".