644144376 has 32 divisors (see below), whose sum is σ = 1633046400. Its totient is φ = 211690080.

The previous prime is 644144363. The next prime is 644144377. The reversal of 644144376 is 673441446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644144377) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187306 + ... + 190713.

It is an arithmetic number, because the mean of its divisors is an integer number (51032700).

Almost surely, 2^644144376 is an apocalyptic number.

It is an amenable number.

644144376 is an abundant number, since it is smaller than the sum of its proper divisors (988902024).

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

644144376 is a wasteful number, since it uses less digits than its factorization.

644144376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378099 (or 378095 counting only the distinct ones).

The product of its digits is 193536, while the sum is 39.

The square root of 644144376 is about 25379.9995271868. Note that the first 3 decimals coincide. The cubic root of 644144376 is about 863.6300392237.

The spelling of 644144376 in words is "six hundred forty-four million, one hundred forty-four thousand, three hundred seventy-six".