644340729 has 16 divisors (see below), whose sum is σ = 869982912. Its totient is φ = 424163328.

The previous prime is 644340713. The next prime is 644340731. The reversal of 644340729 is 927043446.

It is not a de Polignac number, because 644340729 - 2⁴ = 644340713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644340629) 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, 75262 + ... + 83384.

It is an arithmetic number, because the mean of its divisors is an integer number (54373932).

Almost surely, 2^644340729 is an apocalyptic number.

It is an amenable number.

644340729 is a deficient number, since it is larger than the sum of its proper divisors (225642183).

644340729 is a wasteful number, since it uses less digits than its factorization.

644340729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8456.

The product of its (nonzero) digits is 145152, while the sum is 39.

The square root of 644340729 is about 25383.8674949268. The cubic root of 644340729 is about 863.7177830732.

The spelling of 644340729 in words is "six hundred forty-four million, three hundred forty thousand, seven hundred twenty-nine".