21997472 has 36 divisors (see below), whose sum is σ = 50381730. Its totient is φ = 9426816.

The previous prime is 21997463. The next prime is 21997477. The reversal of 21997472 is 27479912.

It can be written as a sum of positive squares in only one way, i.e., 21864976 + 132496 = 4676^2 + 364^2 .

It is not an unprimeable number, because it can be changed into a prime (21997477) 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 5 ways as a sum of consecutive naturals, for example, 5447 + ... + 8582.

Almost surely, 2^21997472 is an apocalyptic number.

It is an amenable number.

21997472 is an abundant number, since it is smaller than the sum of its proper divisors (28384258).

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

21997472 is a wasteful number, since it uses less digits than its factorization.

21997472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14053 (or 14038 counting only the distinct ones).

The product of its digits is 63504, while the sum is 41.

The square root of 21997472 is about 4690.1462663759. The cubic root of 21997472 is about 280.1931999947.

The spelling of 21997472 in words is "twenty-one million, nine hundred ninety-seven thousand, four hundred seventy-two".