646505165 has 4 divisors (see below), whose sum is σ = 775806204. Its totient is φ = 517204128.

The previous prime is 646505143. The next prime is 646505201. The reversal of 646505165 is 561505646.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 381108484 + 265396681 = 19522^2 + 16291^2 .

It is a cyclic number.

It is not a de Polignac number, because 646505165 - 2¹⁰ = 646504141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64650512 + ... + 64650521.

It is an arithmetic number, because the mean of its divisors is an integer number (193951551).

Almost surely, 2^646505165 is an apocalyptic number.

It is an amenable number.

646505165 is a deficient number, since it is larger than the sum of its proper divisors (129301039).

646505165 is a wasteful number, since it uses less digits than its factorization.

646505165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129301038.

The product of its (nonzero) digits is 108000, while the sum is 38.

The square root of 646505165 is about 25426.4658377841. The cubic root of 646505165 is about 864.6838208700.

The spelling of 646505165 in words is "six hundred forty-six million, five hundred five thousand, one hundred sixty-five".