666756197 has 4 divisors (see below), whose sum is σ = 689747820. Its totient is φ = 643764576.

The previous prime is 666756193. The next prime is 666756217. The reversal of 666756197 is 791657666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 105966436 + 560789761 = 10294^2 + 23681^2 .

It is a cyclic number.

It is not a de Polignac number, because 666756197 - 2² = 666756193 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 (666756191) 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, 11495768 + ... + 11495825.

It is an arithmetic number, because the mean of its divisors is an integer number (172436955).

Almost surely, 2^666756197 is an apocalyptic number.

It is an amenable number.

666756197 is a deficient number, since it is larger than the sum of its proper divisors (22991623).

666756197 is a wasteful number, since it uses less digits than its factorization.

666756197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22991622.

The product of its digits is 2857680, while the sum is 53.

The square root of 666756197 is about 25821.6226639613. The cubic root of 666756197 is about 873.6195689609.

The spelling of 666756197 in words is "six hundred sixty-six million, seven hundred fifty-six thousand, one hundred ninety-seven".