21931992 has 32 divisors (see below), whose sum is σ = 60922800. Its totient is φ = 7310592.

The previous prime is 21931979. The next prime is 21931997. The reversal of 21931992 is 29913912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21931997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50553 + ... + 50984.

Almost surely, 2^21931992 is an apocalyptic number.

It is an amenable number.

21931992 is an abundant number, since it is smaller than the sum of its proper divisors (38990808).

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

21931992 is a wasteful number, since it uses less digits than its factorization.

21931992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101552 (or 101542 counting only the distinct ones).

The product of its digits is 8748, while the sum is 36.

The square root of 21931992 is about 4683.1604713057. The cubic root of 21931992 is about 279.9149061148.

The spelling of 21931992 in words is "twenty-one million, nine hundred thirty-one thousand, nine hundred ninety-two".