18307231 has 2 divisors, whose sum is σ = 18307232. Its totient is φ = 18307230.

The previous prime is 18307229. The next prime is 18307253. The reversal of 18307231 is 13270381.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18307231 - 2¹ = 18307229 is a prime.

It is a super-2 number, since 2×18307231² = 670309413774722, which contains 22 as substring.

Together with 18307229, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 18307196 and 18307205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18307291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9153615 + 9153616.

It is an arithmetic number, because the mean of its divisors is an integer number (9153616).

Almost surely, 2^18307231 is an apocalyptic number.

18307231 is a deficient number, since it is larger than the sum of its proper divisors (1).

18307231 is an equidigital number, since it uses as much as digits as its factorization.

18307231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 18307231 is about 4278.6950113323. The cubic root of 18307231 is about 263.5567967324.

The spelling of 18307231 in words is "eighteen million, three hundred seven thousand, two hundred thirty-one".