665566251 has 8 divisors (see below), whose sum is σ = 1014196224. Its totient is φ = 380323560.

The previous prime is 665566229. The next prime is 665566259. The reversal of 665566251 is 152665566.

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

It is not a de Polignac number, because 665566251 - 2⁷ = 665566123 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (665566259) 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, 15846795 + ... + 15846836.

It is an arithmetic number, because the mean of its divisors is an integer number (126774528).

Almost surely, 2^665566251 is an apocalyptic number.

665566251 is a deficient number, since it is larger than the sum of its proper divisors (348629973).

665566251 is a wasteful number, since it uses less digits than its factorization.

665566251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31693641.

The product of its digits is 324000, while the sum is 42.

The square root of 665566251 is about 25798.5707162238. The cubic root of 665566251 is about 873.0995492209.

The spelling of 665566251 in words is "six hundred sixty-five million, five hundred sixty-six thousand, two hundred fifty-one".