644500664744 has 16 divisors (see below), whose sum is σ = 1247420641920. Its totient is φ = 311855160240.

The previous prime is 644500664741. The next prime is 644500664771. The reversal of 644500664744 is 447466005446.

It is a happy number.

644500664744 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644500664744² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644500664692 and 644500664701.

It is not an unprimeable number, because it can be changed into a prime (644500664741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1299396254 + ... + 1299396749.

It is an arithmetic number, because the mean of its divisors is an integer number (77963790120).

Almost surely, 2^644500664744 is an apocalyptic number.

It is an amenable number.

644500664744 is a deficient number, since it is larger than the sum of its proper divisors (602919977176).

644500664744 is a wasteful number, since it uses less digits than its factorization.

644500664744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2598793040 (or 2598793036 counting only the distinct ones).

The product of its (nonzero) digits is 7741440, while the sum is 50.

The spelling of 644500664744 in words is "six hundred forty-four billion, five hundred million, six hundred sixty-four thousand, seven hundred forty-four".