21172580772 has 24 divisors (see below), whose sum is σ = 56460215616. Its totient is φ = 6049308768.

The previous prime is 21172580771. The next prime is 21172580789. The reversal of 21172580772 is 27708527112.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (21172580771) 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, 126027183 + ... + 126027350.

It is an arithmetic number, because the mean of its divisors is an integer number (2352508984).

Almost surely, 2^21172580772 is an apocalyptic number.

It is an amenable number.

21172580772 is an abundant number, since it is smaller than the sum of its proper divisors (35287634844).

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

21172580772 is a wasteful number, since it uses less digits than its factorization.

21172580772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252054547 (or 252054545 counting only the distinct ones).

The product of its (nonzero) digits is 109760, while the sum is 42.

The spelling of 21172580772 in words is "twenty-one billion, one hundred seventy-two million, five hundred eighty thousand, seven hundred seventy-two".