17921972 has 12 divisors (see below), whose sum is σ = 31394916. Its totient is φ = 8952000.

The previous prime is 17921963. The next prime is 17921987. The reversal of 17921972 is 27912971.

It can be written as a sum of positive squares in 2 ways, for example, as 12931216 + 4990756 = 3596^2 + 2234^2 .

It is a congruent number.

It is an unprimeable number.

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, 4472 + ... + 7472.

It is an arithmetic number, because the mean of its divisors is an integer number (2616243).

Almost surely, 2^17921972 is an apocalyptic number.

It is an amenable number.

17921972 is a deficient number, since it is larger than the sum of its proper divisors (13472944).

17921972 is a wasteful number, since it uses less digits than its factorization.

17921972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4498 (or 4496 counting only the distinct ones).

The product of its digits is 15876, while the sum is 38.

The square root of 17921972 is about 4233.4350119023. The cubic root of 17921972 is about 261.6949034850.

Subtracting 17921972 from its reverse (27912971), we obtain a palindrome (9990999).

The spelling of 17921972 in words is "seventeen million, nine hundred twenty-one thousand, nine hundred seventy-two".