18611987 has 2 divisors, whose sum is σ = 18611988. Its totient is φ = 18611986.

The previous prime is 18611981. The next prime is 18612019. The reversal of 18611987 is 78911681.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18611987 - 2⁸ = 18611731 is a prime.

It is not a weakly prime, because it can be changed into another prime (18611981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9305993 + 9305994.

It is an arithmetic number, because the mean of its divisors is an integer number (9305994).

Almost surely, 2^18611987 is an apocalyptic number.

18611987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18611987 is an equidigital number, since it uses as much as digits as its factorization.

18611987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 41.

The square root of 18611987 is about 4314.1612162737. The cubic root of 18611987 is about 265.0112111075.

The spelling of 18611987 in words is "eighteen million, six hundred eleven thousand, nine hundred eighty-seven".