644742696 has 64 divisors (see below), whose sum is σ = 1742973120. Its totient is φ = 197568000.

The previous prime is 644742677. The next prime is 644742719. The reversal of 644742696 is 696247446.

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 15 ways as a sum of consecutive naturals, for example, 74196 + ... + 82428.

It is an arithmetic number, because the mean of its divisors is an integer number (27233955).

Almost surely, 2^644742696 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644742696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871486560).

644742696 is an abundant number, since it is smaller than the sum of its proper divisors (1098230424).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644742696 is a wasteful number, since it uses less digits than its factorization.

644742696 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8506 (or 8502 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 48.

The square root of 644742696 is about 25391.7840255465. The cubic root of 644742696 is about 863.8973536322.

The spelling of 644742696 in words is "six hundred forty-four million, seven hundred forty-two thousand, six hundred ninety-six".