665161665 has 16 divisors (see below), whose sum is σ = 1216295808. Its totient is φ = 304073856.

The previous prime is 665161663. The next prime is 665161681. The reversal of 665161665 is 566161566.

It is not a de Polignac number, because 665161665 - 2¹ = 665161663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665161663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3167332 + ... + 3167541.

It is an arithmetic number, because the mean of its divisors is an integer number (76018488).

Almost surely, 2^665161665 is an apocalyptic number.

It is an amenable number.

665161665 is a deficient number, since it is larger than the sum of its proper divisors (551134143).

665161665 is a wasteful number, since it uses less digits than its factorization.

665161665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6334888.

The product of its digits is 194400, while the sum is 42.

The square root of 665161665 is about 25790.7282758746. The cubic root of 665161665 is about 872.9225994158.

Subtracting from 665161665 its reverse (566161566), we obtain a palindrome (99000099).

The spelling of 665161665 in words is "six hundred sixty-five million, one hundred sixty-one thousand, six hundred sixty-five".