18013181 has 2 divisors, whose sum is σ = 18013182. Its totient is φ = 18013180.

The previous prime is 18013153. The next prime is 18013187. The reversal of 18013181 is 18131081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16736281 + 1276900 = 4091^2 + 1130^2 .

It is an emirp because it is prime and its reverse (18131081) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18013181 is a prime.

It is a super-2 number, since 2×18013181² = 648949379477522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18013187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9006590 + 9006591.

It is an arithmetic number, because the mean of its divisors is an integer number (9006591).

Almost surely, 2^18013181 is an apocalyptic number.

It is an amenable number.

18013181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18013181 is an equidigital number, since it uses as much as digits as its factorization.

18013181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 23.

The square root of 18013181 is about 4244.1937985912. The cubic root of 18013181 is about 262.1380941687.

The spelling of 18013181 in words is "eighteen million, thirteen thousand, one hundred eighty-one".