644794326 has 48 divisors (see below), whose sum is σ = 1613718288. Its totient is φ = 183897600.

The previous prime is 644794321. The next prime is 644794369. The reversal of 644794326 is 623497446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644794321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 92415 + ... + 99146.

It is an arithmetic number, because the mean of its divisors is an integer number (33619131).

Almost surely, 2^644794326 is an apocalyptic number.

644794326 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

644794326 is an abundant number, since it is smaller than the sum of its proper divisors (968923962).

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

644794326 is a wasteful number, since it uses less digits than its factorization.

644794326 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191597 (or 191594 counting only the distinct ones).

The product of its digits is 870912, while the sum is 45.

The square root of 644794326 is about 25392.8006726316. The cubic root of 644794326 is about 863.9204128723.

The spelling of 644794326 in words is "six hundred forty-four million, seven hundred ninety-four thousand, three hundred twenty-six".