18221815 has 8 divisors (see below), whose sum is σ = 22060368. Its totient is φ = 14448000.

The previous prime is 18221783. The next prime is 18221821. The reversal of 18221815 is 51812281.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18221815 - 2⁵ = 18221783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15561 + ... + 16690.

It is an arithmetic number, because the mean of its divisors is an integer number (2757546).

Almost surely, 2^18221815 is an apocalyptic number.

18221815 is a deficient number, since it is larger than the sum of its proper divisors (3838553).

18221815 is a wasteful number, since it uses less digits than its factorization.

18221815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32369.

The product of its digits is 1280, while the sum is 28.

The square root of 18221815 is about 4268.7017932856. The cubic root of 18221815 is about 263.1462655107.

The spelling of 18221815 in words is "eighteen million, two hundred twenty-one thousand, eight hundred fifteen".