644355140 has 48 divisors (see below), whose sum is σ = 1589716800. Its totient is φ = 216286080.

The previous prime is 644355133. The next prime is 644355149. The reversal of 644355140 is 41553446.

It is a junction number, because it is equal to n+sod(n) for n = 644355097 and 644355106.

It is not an unprimeable number, because it can be changed into a prime (644355149) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109790 + ... + 115509.

It is an arithmetic number, because the mean of its divisors is an integer number (33119100).

Almost surely, 2^644355140 is an apocalyptic number.

It is an amenable number.

644355140 is an abundant number, since it is smaller than the sum of its proper divisors (945361660).

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

644355140 is a wasteful number, since it uses less digits than its factorization.

644355140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225332 (or 225330 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 32.

The square root of 644355140 is about 25384.1513547331. The cubic root of 644355140 is about 863.7242221841.

The spelling of 644355140 in words is "six hundred forty-four million, three hundred fifty-five thousand, one hundred forty".