21705521172 has 48 divisors (see below), whose sum is σ = 50906705472. Its totient is φ = 7198009600.

The previous prime is 21705521147. The next prime is 21705521177. The reversal of 21705521172 is 27112550712.

It is a super-2 number, since 2×21705521172² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705521177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5862922 + ... + 5866622.

It is an arithmetic number, because the mean of its divisors is an integer number (1060556364).

Almost surely, 2^21705521172 is an apocalyptic number.

It is an amenable number.

21705521172 is an abundant number, since it is smaller than the sum of its proper divisors (29201184300).

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

21705521172 is a wasteful number, since it uses less digits than its factorization.

21705521172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6088 (or 6086 counting only the distinct ones).

The product of its (nonzero) digits is 9800, while the sum is 33.

The spelling of 21705521172 in words is "twenty-one billion, seven hundred five million, five hundred twenty-one thousand, one hundred seventy-two".