644787240 has 64 divisors (see below), whose sum is σ = 1949175360. Its totient is φ = 170626560.

The previous prime is 644787239. The next prime is 644787251. The reversal of 644787240 is 42787446.

It is a junction number, because it is equal to n+sod(n) for n = 644787192 and 644787201.

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, 4789 + ... + 36228.

It is an arithmetic number, because the mean of its divisors is an integer number (30455865).

Almost surely, 2^644787240 is an apocalyptic number.

644787240 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644787240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (974587680).

644787240 is an abundant number, since it is smaller than the sum of its proper divisors (1304388120).

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

644787240 is a wasteful number, since it uses less digits than its factorization.

644787240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41162 (or 41158 counting only the distinct ones).

The product of its (nonzero) digits is 301056, while the sum is 42.

The square root of 644787240 is about 25392.6611445118. The cubic root of 644787240 is about 863.9172481616.

The spelling of 644787240 in words is "six hundred forty-four million, seven hundred eighty-seven thousand, two hundred forty".