644042488 has 8 divisors (see below), whose sum is σ = 1207579680. Its totient is φ = 322021240.

The previous prime is 644042479. The next prime is 644042489. The reversal of 644042488 is 884240446.

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

It is a self number, because there is not a number n which added to its sum of digits gives 644042488.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644042489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40252648 + ... + 40252663.

It is an arithmetic number, because the mean of its divisors is an integer number (150947460).

Almost surely, 2^644042488 is an apocalyptic number.

It is an amenable number.

644042488 is a deficient number, since it is larger than the sum of its proper divisors (563537192).

644042488 is a wasteful number, since it uses less digits than its factorization.

644042488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80505317 (or 80505313 counting only the distinct ones).

The product of its (nonzero) digits is 196608, while the sum is 40.

The square root of 644042488 is about 25377.9921979655. The cubic root of 644042488 is about 863.5845017218.

The spelling of 644042488 in words is "six hundred forty-four million, forty-two thousand, four hundred eighty-eight".