21572168 has 8 divisors (see below), whose sum is σ = 40447830. Its totient is φ = 10786080.

The previous prime is 21572141. The next prime is 21572179. The reversal of 21572168 is 86127512.

It can be written as a sum of positive squares in only one way, i.e., 20268004 + 1304164 = 4502^2 + 1142^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1348253 + ... + 1348268.

Almost surely, 2^21572168 is an apocalyptic number.

It is an amenable number.

21572168 is a deficient number, since it is larger than the sum of its proper divisors (18875662).

21572168 is a wasteful number, since it uses less digits than its factorization.

21572168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2696527 (or 2696523 counting only the distinct ones).

The product of its digits is 6720, while the sum is 32.

The square root of 21572168 is about 4644.5848038334. The cubic root of 21572168 is about 278.3756631410.

The spelling of 21572168 in words is "twenty-one million, five hundred seventy-two thousand, one hundred sixty-eight".