21172465 has 16 divisors (see below), whose sum is σ = 26484480. Its totient is φ = 16228800.

The previous prime is 21172457. The next prime is 21172483. The reversal of 21172465 is 56427112.

It is not a de Polignac number, because 21172465 - 2³ = 21172457 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21412 + ... + 22378.

It is an arithmetic number, because the mean of its divisors is an integer number (1655280).

Almost surely, 2^21172465 is an apocalyptic number.

It is an amenable number.

21172465 is a deficient number, since it is larger than the sum of its proper divisors (5312015).

21172465 is a wasteful number, since it uses less digits than its factorization.

21172465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1152.

The product of its digits is 3360, while the sum is 28.

The square root of 21172465 is about 4601.3546918272. The cubic root of 21172465 is about 276.6456258897.

Adding to 21172465 its reverse (56427112), we get a palindrome (77599577).

The spelling of 21172465 in words is "twenty-one million, one hundred seventy-two thousand, four hundred sixty-five".