18131831 has 2 divisors, whose sum is σ = 18131832. Its totient is φ = 18131830.

The previous prime is 18131819. The next prime is 18131857. The reversal of 18131831 is 13813181.

It is an a-pointer prime, because the next prime (18131857) can be obtained adding 18131831 to its sum of digits (26).

It is a weak prime.

It is an emirp because it is prime and its reverse (13813181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18131831 - 2²² = 13937527 is a prime.

It is a super-2 number, since 2×18131831² = 657526590825122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18131831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18131431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9065915 + 9065916.

It is an arithmetic number, because the mean of its divisors is an integer number (9065916).

Almost surely, 2^18131831 is an apocalyptic number.

18131831 is a deficient number, since it is larger than the sum of its proper divisors (1).

18131831 is an equidigital number, since it uses as much as digits as its factorization.

18131831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 26.

The square root of 18131831 is about 4258.1487761702. The cubic root of 18131831 is about 262.7123892580.

The spelling of 18131831 in words is "eighteen million, one hundred thirty-one thousand, eight hundred thirty-one".