666308891 has 6 divisors (see below), whose sum is σ = 703223892. Its totient is φ = 631239660.

The previous prime is 666308879. The next prime is 666308899. The reversal of 666308891 is 198803666.

It is not a de Polignac number, because 666308891 - 2¹⁰ = 666307867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666308899) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 922505 + ... + 923226.

It is an arithmetic number, because the mean of its divisors is an integer number (117203982).

Almost surely, 2^666308891 is an apocalyptic number.

666308891 is a deficient number, since it is larger than the sum of its proper divisors (36915001).

666308891 is a wasteful number, since it uses less digits than its factorization.

666308891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1845769 (or 1845750 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 47.

The square root of 666308891 is about 25812.9597489323. The cubic root of 666308891 is about 873.4241638561.

The spelling of 666308891 in words is "six hundred sixty-six million, three hundred eight thousand, eight hundred ninety-one".