665172651 has 64 divisors (see below), whose sum is σ = 1110896640. Its totient is φ = 347811840.

The previous prime is 665172637. The next prime is 665172671. The reversal of 665172651 is 156271566.

It is not a de Polignac number, because 665172651 - 2⁵ = 665172619 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (665172671) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1626135 + ... + 1626543.

It is an arithmetic number, because the mean of its divisors is an integer number (17357760).

Almost surely, 2^665172651 is an apocalyptic number.

665172651 is a deficient number, since it is larger than the sum of its proper divisors (445723989).

665172651 is a wasteful number, since it uses less digits than its factorization.

665172651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676.

The product of its digits is 75600, while the sum is 39.

The square root of 665172651 is about 25790.9412585117. The cubic root of 665172651 is about 872.9274052023.

The spelling of 665172651 in words is "six hundred sixty-five million, one hundred seventy-two thousand, six hundred fifty-one".