21757372 has 36 divisors (see below), whose sum is σ = 47704440. Its totient is φ = 8606304.

The previous prime is 21757361. The next prime is 21757387. The reversal of 21757372 is 27375712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1722 + ... + 6817.

Almost surely, 2^21757372 is an apocalyptic number.

It is an amenable number.

21757372 is an abundant number, since it is smaller than the sum of its proper divisors (25947068).

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

21757372 is a wasteful number, since it uses less digits than its factorization.

21757372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8570 (or 8561 counting only the distinct ones).

The product of its digits is 20580, while the sum is 34.

The square root of 21757372 is about 4664.4798209447. The cubic root of 21757372 is about 279.1700423245.

The spelling of 21757372 in words is "twenty-one million, seven hundred fifty-seven thousand, three hundred seventy-two".