18513631 has 2 divisors, whose sum is σ = 18513632. Its totient is φ = 18513630.

The previous prime is 18513623. The next prime is 18513659. The reversal of 18513631 is 13631581.

It is an a-pointer prime, because the next prime (18513659) can be obtained adding 18513631 to its sum of digits (28).

It is a weak prime.

It is an emirp because it is prime and its reverse (13631581) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18513631 - 2³ = 18513623 is a prime.

It is a super-2 number, since 2×18513631² = 685509065608322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18513631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18513601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9256815 + 9256816.

It is an arithmetic number, because the mean of its divisors is an integer number (9256816).

Almost surely, 2^18513631 is an apocalyptic number.

18513631 is a deficient number, since it is larger than the sum of its proper divisors (1).

18513631 is an equidigital number, since it uses as much as digits as its factorization.

18513631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 18513631 is about 4302.7469133101. The cubic root of 18513631 is about 264.5435645906.

The spelling of 18513631 in words is "eighteen million, five hundred thirteen thousand, six hundred thirty-one".