18959987 has 2 divisors, whose sum is σ = 18959988. Its totient is φ = 18959986.

The previous prime is 18959977. The next prime is 18960031. The reversal of 18959987 is 78995981.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18959987 - 2¹⁰ = 18958963 is a prime.

It is a super-2 number, since 2×18959987² = 718962214080338, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18959977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9479993 + 9479994.

It is an arithmetic number, because the mean of its divisors is an integer number (9479994).

Almost surely, 2^18959987 is an apocalyptic number.

18959987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18959987 is an equidigital number, since it uses as much as digits as its factorization.

18959987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1632960, while the sum is 56.

The square root of 18959987 is about 4354.3067186408. The cubic root of 18959987 is about 266.6527161105.

The spelling of 18959987 in words is "eighteen million, nine hundred fifty-nine thousand, nine hundred eighty-seven".