21718423872 has 84 divisors (see below), whose sum is σ = 64398608820. Its totient is φ = 6989832192.

The previous prime is 21718423871. The next prime is 21718423913. The reversal of 21718423872 is 27832481712.

21718423872 is a `hidden beast` number, since 217 + 1 + 8 + 423 + 8 + 7 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16709181696 + 5009242176 = 129264^2 + 70776^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718423871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 633393 + ... + 666800.

It is an arithmetic number, because the mean of its divisors is an integer number (766650105).

Almost surely, 2^21718423872 is an apocalyptic number.

It is an amenable number.

21718423872 is an abundant number, since it is smaller than the sum of its proper divisors (42680184948).

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

21718423872 is a wasteful number, since it uses less digits than its factorization.

21718423872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1300240 (or 1300227 counting only the distinct ones).

The product of its digits is 301056, while the sum is 45.

The spelling of 21718423872 in words is "twenty-one billion, seven hundred eighteen million, four hundred twenty-three thousand, eight hundred seventy-two".