21897972432 has 80 divisors (see below), whose sum is σ = 71834628480. Its totient is φ = 6256562688.

The previous prime is 21897972409. The next prime is 21897972451. The reversal of 21897972432 is 23427979812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3617673 + ... + 3623720.

It is an arithmetic number, because the mean of its divisors is an integer number (897932856).

Almost surely, 2^21897972432 is an apocalyptic number.

It is an amenable number.

21897972432 is an abundant number, since it is smaller than the sum of its proper divisors (49936656048).

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

21897972432 is a wasteful number, since it uses less digits than its factorization.

21897972432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7241417 (or 7241405 counting only the distinct ones).

The product of its digits is 3048192, while the sum is 54.

The spelling of 21897972432 in words is "twenty-one billion, eight hundred ninety-seven million, nine hundred seventy-two thousand, four hundred thirty-two".