21957611872 has 72 divisors (see below), whose sum is σ = 50507271360. Its totient is φ = 9369158400.

The previous prime is 21957611833. The next prime is 21957611887. The reversal of 21957611872 is 27811675912.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 328497 + ... + 389647.

It is an arithmetic number, because the mean of its divisors is an integer number (701489880).

Almost surely, 2^21957611872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21957611872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25253635680).

21957611872 is an abundant number, since it is smaller than the sum of its proper divisors (28549659488).

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

21957611872 is a wasteful number, since it uses less digits than its factorization.

21957611872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61404 (or 61389 counting only the distinct ones).

The product of its digits is 423360, while the sum is 49.

The spelling of 21957611872 in words is "twenty-one billion, nine hundred fifty-seven million, six hundred eleven thousand, eight hundred seventy-two".