666815707 has 2 divisors, whose sum is σ = 666815708. Its totient is φ = 666815706.

The previous prime is 666815693. The next prime is 666815713. The reversal of 666815707 is 707518666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666815707 - 2²⁷ = 532597979 is a prime.

It is not a weakly prime, because it can be changed into another prime (666815777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333407853 + 333407854.

It is an arithmetic number, because the mean of its divisors is an integer number (333407854).

Almost surely, 2^666815707 is an apocalyptic number.

666815707 is a deficient number, since it is larger than the sum of its proper divisors (1).

666815707 is an equidigital number, since it uses as much as digits as its factorization.

666815707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 423360, while the sum is 46.

The square root of 666815707 is about 25822.7749670712. The cubic root of 666815707 is about 873.6455592475.

The spelling of 666815707 in words is "six hundred sixty-six million, eight hundred fifteen thousand, seven hundred seven".