641661165 has 24 divisors (see below), whose sum is σ = 1114310808. Its totient is φ = 341573760.

The previous prime is 641661101. The next prime is 641661173. The reversal of 641661165 is 561166146.

It is a happy number.

641661165 is a `hidden beast` number, since 641 + 6 + 6 + 1 + 1 + 6 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 27910089 + 613751076 = 5283^2 + 24774^2 .

It is not a de Polignac number, because 641661165 - 2⁶ = 641661101 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11167 + ... + 37523.

It is an arithmetic number, because the mean of its divisors is an integer number (46429617).

Almost surely, 2^641661165 is an apocalyptic number.

It is an amenable number.

641661165 is a deficient number, since it is larger than the sum of its proper divisors (472649643).

641661165 is a wasteful number, since it uses less digits than its factorization.

641661165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26909 (or 26906 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 641661165 is about 25331.0316607911. The cubic root of 641661165 is about 862.5188300867.

The spelling of 641661165 in words is "six hundred forty-one million, six hundred sixty-one thousand, one hundred sixty-five".