18215181 has 12 divisors (see below), whose sum is σ = 26362908. Its totient is φ = 12119424.

The previous prime is 18215159. The next prime is 18215189. The reversal of 18215181 is 18151281.

It can be written as a sum of positive squares in 2 ways, for example, as 14699556 + 3515625 = 3834^2 + 1875^2 .

It is not a de Polignac number, because 18215181 - 2¹⁵ = 18182413 is a prime.

It is a super-2 number, since 2×18215181² = 663585637725522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18215189) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3631 + ... + 7043.

It is an arithmetic number, because the mean of its divisors is an integer number (2196909).

Almost surely, 2^18215181 is an apocalyptic number.

It is an amenable number.

18215181 is a deficient number, since it is larger than the sum of its proper divisors (8147727).

18215181 is a wasteful number, since it uses less digits than its factorization.

18215181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4012 (or 4009 counting only the distinct ones).

The product of its digits is 640, while the sum is 27.

The square root of 18215181 is about 4267.9246713127. The cubic root of 18215181 is about 263.1143271587.

The spelling of 18215181 in words is "eighteen million, two hundred fifteen thousand, one hundred eighty-one".