666665887 has 2 divisors, whose sum is σ = 666665888. Its totient is φ = 666665886.

The previous prime is 666665873. The next prime is 666665893. The reversal of 666665887 is 788566666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666665887 - 2⁷ = 666665759 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666665807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333332943 + 333332944.

It is an arithmetic number, because the mean of its divisors is an integer number (333332944).

Almost surely, 2^666665887 is an apocalyptic number.

666665887 is a deficient number, since it is larger than the sum of its proper divisors (1).

666665887 is an equidigital number, since it uses as much as digits as its factorization.

666665887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17418240, while the sum is 58.

The square root of 666665887 is about 25819.8738765316. The cubic root of 666665887 is about 873.5801241854.

The spelling of 666665887 in words is "six hundred sixty-six million, six hundred sixty-five thousand, eight hundred eighty-seven".