666718939 has 8 divisors (see below), whose sum is σ = 680613120. Its totient is φ = 652911336.

The previous prime is 666718931. The next prime is 666718957. The reversal of 666718939 is 939817666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666718939 - 2³ = 666718931 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666718939.

It is not an unprimeable number, because it can be changed into a prime (666718931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5967 + ... + 37000.

It is an arithmetic number, because the mean of its divisors is an integer number (85076640).

Almost surely, 2^666718939 is an apocalyptic number.

666718939 is a deficient number, since it is larger than the sum of its proper divisors (13894181).

666718939 is a wasteful number, since it uses less digits than its factorization.

666718939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43289.

The product of its digits is 2939328, while the sum is 55.

The square root of 666718939 is about 25820.9012042570. The cubic root of 666718939 is about 873.6032961842.

The spelling of 666718939 in words is "six hundred sixty-six million, seven hundred eighteen thousand, nine hundred thirty-nine".