18715987 has 2 divisors, whose sum is σ = 18715988. Its totient is φ = 18715986.

The previous prime is 18715979. The next prime is 18716003. The reversal of 18715987 is 78951781.

It is a weak prime.

It is an emirp because it is prime and its reverse (78951781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18715987 - 2³ = 18715979 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18715927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9357993 + 9357994.

It is an arithmetic number, because the mean of its divisors is an integer number (9357994).

Almost surely, 2^18715987 is an apocalyptic number.

18715987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18715987 is an equidigital number, since it uses as much as digits as its factorization.

18715987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 141120, while the sum is 46.

The square root of 18715987 is about 4326.1977532240. The cubic root of 18715987 is about 265.5039041468.

The spelling of 18715987 in words is "eighteen million, seven hundred fifteen thousand, nine hundred eighty-seven".