18687731 has 2 divisors, whose sum is σ = 18687732. Its totient is φ = 18687730.

The previous prime is 18687587. The next prime is 18687737. The reversal of 18687731 is 13778681.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18687731 - 2¹⁸ = 18425587 is a prime.

It is a super-2 number, since 2×18687731² = 698462579856722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18687737) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9343865 + 9343866.

It is an arithmetic number, because the mean of its divisors is an integer number (9343866).

Almost surely, 2^18687731 is an apocalyptic number.

18687731 is a deficient number, since it is larger than the sum of its proper divisors (1).

18687731 is an equidigital number, since it uses as much as digits as its factorization.

18687731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 41.

The square root of 18687731 is about 4322.9308345149. The cubic root of 18687731 is about 265.3702241928.

The spelling of 18687731 in words is "eighteen million, six hundred eighty-seven thousand, seven hundred thirty-one".