18172516 has 6 divisors (see below), whose sum is σ = 31801910. Its totient is φ = 9086256.

The previous prime is 18172489. The next prime is 18172519. The reversal of 18172516 is 61527181.

It can be written as a sum of positive squares in only one way, i.e., 11902500 + 6270016 = 3450^2 + 2504^2 .

It is not an unprimeable number, because it can be changed into a prime (18172519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2271561 + ... + 2271568.

Almost surely, 2^18172516 is an apocalyptic number.

It is an amenable number.

18172516 is a deficient number, since it is larger than the sum of its proper divisors (13629394).

18172516 is a wasteful number, since it uses less digits than its factorization.

18172516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4543133 (or 4543131 counting only the distinct ones).

The product of its digits is 3360, while the sum is 31.

The square root of 18172516 is about 4262.9234100556. The cubic root of 18172516 is about 262.9087376779.

Adding to 18172516 its reverse (61527181), we get a palindrome (79699697).

The spelling of 18172516 in words is "eighteen million, one hundred seventy-two thousand, five hundred sixteen".