665981279 has 8 divisors (see below), whose sum is σ = 668988432. Its totient is φ = 662981760.

The previous prime is 665981227. The next prime is 665981287. The reversal of 665981279 is 972189566.

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 665981279 - 2¹² = 665977183 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 665981279.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665981209) 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, 232832 + ... + 235674.

It is an arithmetic number, because the mean of its divisors is an integer number (83623554).

Almost surely, 2^665981279 is an apocalyptic number.

665981279 is a deficient number, since it is larger than the sum of its proper divisors (3007153).

665981279 is a wasteful number, since it uses less digits than its factorization.

665981279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3817.

The product of its digits is 1632960, while the sum is 53.

The square root of 665981279 is about 25806.6130865714. The cubic root of 665981279 is about 873.2809914470.

The spelling of 665981279 in words is "six hundred sixty-five million, nine hundred eighty-one thousand, two hundred seventy-nine".