21406352172 has 24 divisors (see below), whose sum is σ = 52119814656. Its totient is φ = 6825213648.

The previous prime is 21406352141. The next prime is 21406352207. The reversal of 21406352172 is 27125360412.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 38779348 + ... + 38779899.

It is an arithmetic number, because the mean of its divisors is an integer number (2171658944).

Almost surely, 2^21406352172 is an apocalyptic number.

It is an amenable number.

21406352172 is an abundant number, since it is smaller than the sum of its proper divisors (30713462484).

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

21406352172 is a wasteful number, since it uses less digits than its factorization.

21406352172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77559277 (or 77559275 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 33.

The spelling of 21406352172 in words is "twenty-one billion, four hundred six million, three hundred fifty-two thousand, one hundred seventy-two".