18221805 has 24 divisors (see below), whose sum is σ = 36097152. Its totient is φ = 8329824.

The previous prime is 18221783. The next prime is 18221821. The reversal of 18221805 is 50812281.

It is not a de Polignac number, because 18221805 - 2⁷ = 18221677 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28609 + ... + 29238.

It is an arithmetic number, because the mean of its divisors is an integer number (1504048).

Almost surely, 2^18221805 is an apocalyptic number.

18221805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18221805 is a deficient number, since it is larger than the sum of its proper divisors (17875347).

18221805 is a wasteful number, since it uses less digits than its factorization.

18221805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57865 (or 57862 counting only the distinct ones).

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

The square root of 18221805 is about 4268.7006219692. The cubic root of 18221805 is about 263.1462173731.

The spelling of 18221805 in words is "eighteen million, two hundred twenty-one thousand, eight hundred five".