18172881 has 24 divisors (see below), whose sum is σ = 28481544. Its totient is φ = 11120640.

The previous prime is 18172877. The next prime is 18172897. The reversal of 18172881 is 18827181.

It can be written as a sum of positive squares in 4 ways, for example, as 25281 + 18147600 = 159^2 + 4260^2 .

It is not a de Polignac number, because 18172881 - 2² = 18172877 is a prime.

It is a super-2 number, since 2×18172881² = 660507207680322, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18172871) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4825 + ... + 7721.

It is an arithmetic number, because the mean of its divisors is an integer number (1186731).

Almost surely, 2^18172881 is an apocalyptic number.

It is an amenable number.

18172881 is a deficient number, since it is larger than the sum of its proper divisors (10308663).

18172881 is a wasteful number, since it uses less digits than its factorization.

18172881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961 (or 2958 counting only the distinct ones).

The product of its digits is 7168, while the sum is 36.

The square root of 18172881 is about 4262.9662208373. The cubic root of 18172881 is about 262.9104978643.

The spelling of 18172881 in words is "eighteen million, one hundred seventy-two thousand, eight hundred eighty-one".