21919972 has 24 divisors (see below), whose sum is σ = 39432960. Its totient is φ = 10657920.

The previous prime is 21919957. The next prime is 21919979. The reversal of 21919972 is 27991912.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21919979) 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 7 ways as a sum of consecutive naturals, for example, 21948 + ... + 22924.

It is an arithmetic number, because the mean of its divisors is an integer number (1643040).

Almost surely, 2^21919972 is an apocalyptic number.

It is an amenable number.

21919972 is a deficient number, since it is larger than the sum of its proper divisors (17512988).

21919972 is a wasteful number, since it uses less digits than its factorization.

21919972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131 (or 1129 counting only the distinct ones).

The product of its digits is 20412, while the sum is 40.

The square root of 21919972 is about 4681.8769740351. The cubic root of 21919972 is about 279.8637602511.

The spelling of 21919972 in words is "twenty-one million, nine hundred nineteen thousand, nine hundred seventy-two".