21144972 has 24 divisors (see below), whose sum is σ = 49718592. Its totient is φ = 6994000.

The previous prime is 21144953. The next prime is 21144989. The reversal of 21144972 is 27944112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5154 + ... + 8297.

It is an arithmetic number, because the mean of its divisors is an integer number (2071608).

Almost surely, 2^21144972 is an apocalyptic number.

It is an amenable number.

21144972 is an abundant number, since it is smaller than the sum of its proper divisors (28573620).

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

21144972 is a wasteful number, since it uses less digits than its factorization.

21144972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13589 (or 13587 counting only the distinct ones).

The product of its digits is 4032, while the sum is 30.

The square root of 21144972 is about 4598.3662316088. The cubic root of 21144972 is about 276.5258301600.

The spelling of 21144972 in words is "twenty-one million, one hundred forty-four thousand, nine hundred seventy-two".