18221660 has 24 divisors (see below), whose sum is σ = 38356080. Its totient is φ = 7271424.

The previous prime is 18221659. The next prime is 18221677. The reversal of 18221660 is 6612281.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10751 + ... + 12329.

It is an arithmetic number, because the mean of its divisors is an integer number (1598170).

Almost surely, 2^18221660 is an apocalyptic number.

18221660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18221660 is an abundant number, since it is smaller than the sum of its proper divisors (20134420).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18221660 is a wasteful number, since it uses less digits than its factorization.

18221660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2165 (or 2163 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 18221660 is about 4268.6836378443. The cubic root of 18221660 is about 263.1455193759.

It can be divided in two parts, 18221 and 660, that added together give a palindrome (18881).

The spelling of 18221660 in words is "eighteen million, two hundred twenty-one thousand, six hundred sixty".