666977917 has 8 divisors (see below), whose sum is σ = 686573496. Its totient is φ = 647642112.

The previous prime is 666977911. The next prime is 666977923. The reversal of 666977917 is 719779666.

It is an interprime number because it is at equal distance from previous prime (666977911) and next prime (666977923).

It can be written as a sum of positive squares in 4 ways, for example, as 180069561 + 486908356 = 13419^2 + 22066^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666977917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666977911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 59728 + ... + 70009.

It is an arithmetic number, because the mean of its divisors is an integer number (85821687).

Almost surely, 2^666977917 is an apocalyptic number.

It is an amenable number.

666977917 is a deficient number, since it is larger than the sum of its proper divisors (19595579).

666977917 is a wasteful number, since it uses less digits than its factorization.

666977917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129887.

The product of its digits is 6001128, while the sum is 58.

The square root of 666977917 is about 25825.9156081638. The cubic root of 666977917 is about 873.7163946898.

The spelling of 666977917 in words is "six hundred sixty-six million, nine hundred seventy-seven thousand, nine hundred seventeen".