21660725172 has 24 divisors (see below), whose sum is σ = 50632446816. Its totient is φ = 7207276768.

The previous prime is 21660725143. The next prime is 21660725179. The reversal of 21660725172 is 27152706612.

It is a self number, because there is not a number n which added to its sum of digits gives 21660725172.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660725179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1613658 + ... + 1627025.

It is an arithmetic number, because the mean of its divisors is an integer number (2109685284).

Almost surely, 2^21660725172 is an apocalyptic number.

It is an amenable number.

21660725172 is an abundant number, since it is smaller than the sum of its proper divisors (28971721644).

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

21660725172 is a wasteful number, since it uses less digits than its factorization.

21660725172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3241247 (or 3241245 counting only the distinct ones).

The product of its (nonzero) digits is 70560, while the sum is 39.

The spelling of 21660725172 in words is "twenty-one billion, six hundred sixty million, seven hundred twenty-five thousand, one hundred seventy-two".