644073743 has 4 divisors (see below), whose sum is σ = 647930640. Its totient is φ = 640216848.

The previous prime is 644073707. The next prime is 644073779. The reversal of 644073743 is 347370446.

644073743 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (644073707) and next prime (644073779).

It is a cyclic number.

It is not a de Polignac number, because 644073743 - 2¹⁶ = 644008207 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644073697 and 644073706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644072743) 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, 1928198 + ... + 1928531.

It is an arithmetic number, because the mean of its divisors is an integer number (161982660).

Almost surely, 2^644073743 is an apocalyptic number.

644073743 is a deficient number, since it is larger than the sum of its proper divisors (3856897).

644073743 is a wasteful number, since it uses less digits than its factorization.

644073743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3856896.

The product of its (nonzero) digits is 169344, while the sum is 38.

The square root of 644073743 is about 25378.6079799504. The cubic root of 644073743 is about 863.5984712437.

The spelling of 644073743 in words is "six hundred forty-four million, seventy-three thousand, seven hundred forty-three".