18218815 has 32 divisors (see below), whose sum is σ = 25272000. Its totient is φ = 12515328.

The previous prime is 18218807. The next prime is 18218819. The reversal of 18218815 is 51881281.

It is a cyclic number.

It is not a de Polignac number, because 18218815 - 2³ = 18218807 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18218819) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 46641 + ... + 47029.

It is an arithmetic number, because the mean of its divisors is an integer number (789750).

Almost surely, 2^18218815 is an apocalyptic number.

18218815 is a deficient number, since it is larger than the sum of its proper divisors (7053185).

18218815 is a wasteful number, since it uses less digits than its factorization.

18218815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459.

The product of its digits is 5120, while the sum is 34.

The square root of 18218815 is about 4268.3503839305. The cubic root of 18218815 is about 263.1318234417.

The spelling of 18218815 in words is "eighteen million, two hundred eighteen thousand, eight hundred fifteen".