646723565 has 4 divisors (see below), whose sum is σ = 776068284. Its totient is φ = 517378848.

The previous prime is 646723559. The next prime is 646723579. The reversal of 646723565 is 565327646.

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 387223684 + 259499881 = 19678^2 + 16109^2 .

It is a cyclic number.

It is not a de Polignac number, because 646723565 - 2¹⁴ = 646707181 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64672352 + ... + 64672361.

It is an arithmetic number, because the mean of its divisors is an integer number (194017071).

Almost surely, 2^646723565 is an apocalyptic number.

It is an amenable number.

646723565 is a deficient number, since it is larger than the sum of its proper divisors (129344719).

646723565 is a wasteful number, since it uses less digits than its factorization.

646723565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129344718.

The product of its digits is 907200, while the sum is 44.

The square root of 646723565 is about 25430.7602127817. The cubic root of 646723565 is about 864.7811780119.

The spelling of 646723565 in words is "six hundred forty-six million, seven hundred twenty-three thousand, five hundred sixty-five".