666667987 has 2 divisors, whose sum is σ = 666667988. Its totient is φ = 666667986.

The previous prime is 666667951. The next prime is 666667993. The reversal of 666667987 is 789766666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666667987 - 2²³ = 658279379 is a prime.

It is not a weakly prime, because it can be changed into another prime (666667907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333333993 + 333333994.

It is an arithmetic number, because the mean of its divisors is an integer number (333333994).

Almost surely, 2^666667987 is an apocalyptic number.

666667987 is a deficient number, since it is larger than the sum of its proper divisors (1).

666667987 is an equidigital number, since it uses as much as digits as its factorization.

666667987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27433728, while the sum is 61.

The square root of 666667987 is about 25819.9145428485. The cubic root of 666667987 is about 873.5810414446.

The spelling of 666667987 in words is "six hundred sixty-six million, six hundred sixty-seven thousand, nine hundred eighty-seven".