644209265 has 16 divisors (see below), whose sum is σ = 883975680. Its totient is φ = 441499200.

The previous prime is 644209243. The next prime is 644209283. The reversal of 644209265 is 562902446.

It is not a de Polignac number, because 644209265 - 2¹⁴ = 644192881 is a prime.

It is a super-2 number, since 2×644209265² = 830011154223680450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78371 + ... + 86199.

It is an arithmetic number, because the mean of its divisors is an integer number (55248480).

Almost surely, 2^644209265 is an apocalyptic number.

It is an amenable number.

644209265 is a deficient number, since it is larger than the sum of its proper divisors (239766415).

644209265 is a wasteful number, since it uses less digits than its factorization.

644209265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10192.

The product of its (nonzero) digits is 103680, while the sum is 38.

The square root of 644209265 is about 25381.2778441118. The cubic root of 644209265 is about 863.6590380062.

The spelling of 644209265 in words is "six hundred forty-four million, two hundred nine thousand, two hundred sixty-five".