646672165 has 4 divisors (see below), whose sum is σ = 776006604. Its totient is φ = 517337728.

The previous prime is 646672151. The next prime is 646672177. The reversal of 646672165 is 561276646.

It is a happy number.

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 349764804 + 296907361 = 18702^2 + 17231^2 .

It is a cyclic number.

It is not a de Polignac number, because 646672165 - 2²¹ = 644575013 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, 64667212 + ... + 64667221.

It is an arithmetic number, because the mean of its divisors is an integer number (194001651).

Almost surely, 2^646672165 is an apocalyptic number.

It is an amenable number.

646672165 is a deficient number, since it is larger than the sum of its proper divisors (129334439).

646672165 is a wasteful number, since it uses less digits than its factorization.

646672165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129334438.

The product of its digits is 362880, while the sum is 43.

The square root of 646672165 is about 25429.7496055309. The cubic root of 646672165 is about 864.7582671772.

The spelling of 646672165 in words is "six hundred forty-six million, six hundred seventy-two thousand, one hundred sixty-five".