644806264 has 8 divisors (see below), whose sum is σ = 1209011760. Its totient is φ = 322403128.

The previous prime is 644806247. The next prime is 644806307. The reversal of 644806264 is 462608446.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40300384 + ... + 40300399.

It is an arithmetic number, because the mean of its divisors is an integer number (151126470).

Almost surely, 2^644806264 is an apocalyptic number.

It is an amenable number.

644806264 is a deficient number, since it is larger than the sum of its proper divisors (564205496).

644806264 is a wasteful number, since it uses less digits than its factorization.

644806264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80600789 (or 80600785 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 40.

The square root of 644806264 is about 25393.0357381704. The cubic root of 644806264 is about 863.9257445043.

The spelling of 644806264 in words is "six hundred forty-four million, eight hundred six thousand, two hundred sixty-four".