18220181 has 16 divisors (see below), whose sum is σ = 21561984. Its totient is φ = 15073344.

The previous prime is 18220171. The next prime is 18220193. The reversal of 18220181 is 18102281.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 18220181 - 2²² = 14025877 is a prime.

It is a super-2 number, since 2×18220181² = 663949991345522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18220121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24491 + ... + 25223.

It is an arithmetic number, because the mean of its divisors is an integer number (1347624).

Almost surely, 2^18220181 is an apocalyptic number.

It is an amenable number.

18220181 is a deficient number, since it is larger than the sum of its proper divisors (3341803).

18220181 is an equidigital number, since it uses as much as digits as its factorization.

18220181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860.

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 18220181 is about 4268.5103959110. The cubic root of 18220181 is about 263.1383995937.

The spelling of 18220181 in words is "eighteen million, two hundred twenty thousand, one hundred eighty-one".