18220988 has 6 divisors (see below), whose sum is σ = 31886736. Its totient is φ = 9110492.

The previous prime is 18220987. The next prime is 18220999. The reversal of 18220988 is 88902281.

It is a super-2 number, since 2×18220988² = 664008807392288, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18220987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2277620 + ... + 2277627.

It is an arithmetic number, because the mean of its divisors is an integer number (5314456).

Almost surely, 2^18220988 is an apocalyptic number.

It is an amenable number.

18220988 is a deficient number, since it is larger than the sum of its proper divisors (13665748).

18220988 is a wasteful number, since it uses less digits than its factorization.

18220988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4555251 (or 4555249 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 38.

The square root of 18220988 is about 4268.6049243283. The cubic root of 18220988 is about 263.1422844719.

The spelling of 18220988 in words is "eighteen million, two hundred twenty thousand, nine hundred eighty-eight".