665660257551 has 10 divisors (see below), whose sum is σ = 994381372512. Its totient is φ = 443773504980.

The previous prime is 665660257547. The next prime is 665660257607. The reversal of 665660257551 is 155752066566.

665660257551 is a `hidden beast` number, since 6 + 6 + 5 + 6 + 60 + 2 + 575 + 5 + 1 = 666.

It is not a de Polignac number, because 665660257551 - 2² = 665660257547 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665660257351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4109013855 + ... + 4109014016.

Almost surely, 2^665660257551 is an apocalyptic number.

665660257551 is a deficient number, since it is larger than the sum of its proper divisors (328721114961).

665660257551 is an equidigital number, since it uses as much as digits as its factorization.

665660257551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8218027883 (or 8218027874 counting only the distinct ones).

The product of its (nonzero) digits is 11340000, while the sum is 54.

The spelling of 665660257551 in words is "six hundred sixty-five billion, six hundred sixty million, two hundred fifty-seven thousand, five hundred fifty-one".