18220815 has 32 divisors (see below), whose sum is σ = 32659200. Its totient is φ = 9637920.

The previous prime is 18220799. The next prime is 18220823. The reversal of 18220815 is 51802281.

It is not a de Polignac number, because 18220815 - 2⁴ = 18220799 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18280 + ... + 19250.

It is an arithmetic number, because the mean of its divisors is an integer number (1020600).

Almost surely, 2^18220815 is an apocalyptic number.

18220815 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

18220815 is a deficient number, since it is larger than the sum of its proper divisors (14438385).

18220815 is a wasteful number, since it uses less digits than its factorization.

18220815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1124 (or 1118 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 18220815 is about 4268.5846600483. The cubic root of 18220815 is about 263.1414516638.

The spelling of 18220815 in words is "eighteen million, two hundred twenty thousand, eight hundred fifteen".