21787372 has 12 divisors (see below), whose sum is σ = 38239600. Its totient is φ = 10861776.

The previous prime is 21787313. The next prime is 21787373. The reversal of 21787372 is 27378712.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21787373) 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 3 ways as a sum of consecutive naturals, for example, 6408 + ... + 9199.

Almost surely, 2^21787372 is an apocalyptic number.

It is an amenable number.

21787372 is a deficient number, since it is larger than the sum of its proper divisors (16452228).

21787372 is a wasteful number, since it uses less digits than its factorization.

21787372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15960 (or 15958 counting only the distinct ones).

The product of its digits is 32928, while the sum is 37.

The square root of 21787372 is about 4667.6945058562. The cubic root of 21787372 is about 279.2982939488.

The spelling of 21787372 in words is "twenty-one million, seven hundred eighty-seven thousand, three hundred seventy-two".