21981272 has 16 divisors (see below), whose sum is σ = 43639560. Its totient is φ = 10344064.

The previous prime is 21981251. The next prime is 21981283. The reversal of 21981272 is 27218912.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80678 + ... + 80949.

Almost surely, 2^21981272 is an apocalyptic number.

It is an amenable number.

21981272 is a deficient number, since it is larger than the sum of its proper divisors (21658288).

21981272 is a wasteful number, since it uses less digits than its factorization.

21981272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161650 (or 161646 counting only the distinct ones).

The product of its digits is 4032, while the sum is 32.

The square root of 21981272 is about 4688.4189232619. The cubic root of 21981272 is about 280.1244005045.

The spelling of 21981272 in words is "twenty-one million, nine hundred eighty-one thousand, two hundred seventy-two".