666747997 has 4 divisors (see below), whose sum is σ = 666885760. Its totient is φ = 666610236.

The previous prime is 666747953. The next prime is 666748013. The reversal of 666747997 is 799747666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 666747997 - 2¹⁵ = 666715229 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 (666747947) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61347 + ... + 71392.

It is an arithmetic number, because the mean of its divisors is an integer number (166721440).

Almost surely, 2^666747997 is an apocalyptic number.

It is an amenable number.

666747997 is a deficient number, since it is larger than the sum of its proper divisors (137763).

666747997 is a wasteful number, since it uses less digits than its factorization.

666747997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137762.

The product of its digits is 24004512, while the sum is 61.

The square root of 666747997 is about 25821.4638818174. The cubic root of 666747997 is about 873.6159875870.

The spelling of 666747997 in words is "six hundred sixty-six million, seven hundred forty-seven thousand, nine hundred ninety-seven".