18615631 has 2 divisors, whose sum is σ = 18615632. Its totient is φ = 18615630.

The previous prime is 18615617. The next prime is 18615637. The reversal of 18615631 is 13651681.

It is a strong prime.

It is an emirp because it is prime and its reverse (13651681) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18615631 is a prime.

It is a super-2 number, since 2×18615631² = 693083435056322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18615593 and 18615602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18615637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9307815 + 9307816.

It is an arithmetic number, because the mean of its divisors is an integer number (9307816).

Almost surely, 2^18615631 is an apocalyptic number.

18615631 is a deficient number, since it is larger than the sum of its proper divisors (1).

18615631 is an equidigital number, since it uses as much as digits as its factorization.

18615631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 18615631 is about 4314.5835256720. The cubic root of 18615631 is about 265.0285052996.

The spelling of 18615631 in words is "eighteen million, six hundred fifteen thousand, six hundred thirty-one".