18487691 has 2 divisors, whose sum is σ = 18487692. Its totient is φ = 18487690.

The previous prime is 18487681. The next prime is 18487723. The reversal of 18487691 is 19678481.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18487691 is a prime.

It is a super-2 number, since 2×18487691² = 683589437022962, 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 (18487621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9243845 + 9243846.

It is an arithmetic number, because the mean of its divisors is an integer number (9243846).

Almost surely, 2^18487691 is an apocalyptic number.

18487691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18487691 is an equidigital number, since it uses as much as digits as its factorization.

18487691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96768, while the sum is 44.

The square root of 18487691 is about 4299.7315032453. The cubic root of 18487691 is about 264.4199535508.

The spelling of 18487691 in words is "eighteen million, four hundred eighty-seven thousand, six hundred ninety-one".