18188181 has 48 divisors (see below), whose sum is σ = 30932928. Its totient is φ = 10176000.

The previous prime is 18188173. The next prime is 18188189.

18188181 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (18188173) and next prime (18188189).

It is not a de Polignac number, because 18188181 - 2³ = 18188173 is a prime.

It is a super-2 number, since 2×18188181² = 661619856177522, which contains 22 as substring.

18188181 is a strobogrammatic number because it is the same when read upside-down.

18188181 is a modest number, since divided by 8181 gives 1818 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18188189) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 169930 + ... + 170036.

It is an arithmetic number, because the mean of its divisors is an integer number (644436).

Almost surely, 2^18188181 is an apocalyptic number.

18188181 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18188181 is a deficient number, since it is larger than the sum of its proper divisors (12744747).

18188181 is a wasteful number, since it uses less digits than its factorization.

18188181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 239 counting only the distinct ones).

The product of its digits is 4096, while the sum is 36.

The square root of 18188181 is about 4264.7603684146. The cubic root of 18188181 is about 262.9842598299.

It can be divided in two parts, 1818 and 8181, that added together give a palindrome (9999).

The spelling of 18188181 in words is "eighteen million, one hundred eighty-eight thousand, one hundred eighty-one".