18331231 has 2 divisors, whose sum is σ = 18331232. Its totient is φ = 18331230.

The previous prime is 18331217. The next prime is 18331259. The reversal of 18331231 is 13213381.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18331231 - 2¹⁷ = 18200159 is a prime.

It is a super-2 number, since 2×18331231² = 672068059950722, 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 (18331031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9165615 + 9165616.

It is an arithmetic number, because the mean of its divisors is an integer number (9165616).

It is a self-describing number.

Almost surely, 2^18331231 is an apocalyptic number.

18331231 is a deficient number, since it is larger than the sum of its proper divisors (1).

18331231 is an equidigital number, since it uses as much as digits as its factorization.

18331231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 22.

The square root of 18331231 is about 4281.4986862079. The cubic root of 18331231 is about 263.6719170190.

The spelling of 18331231 in words is "eighteen million, three hundred thirty-one thousand, two hundred thirty-one".