644046071 has 4 divisors (see below), whose sum is σ = 681931152. Its totient is φ = 606160992.

The previous prime is 644046031. The next prime is 644046103. The reversal of 644046071 is 170640446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 170640446 = 2 ⋅85320223.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644046071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644046031) 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, 18942515 + ... + 18942548.

It is an arithmetic number, because the mean of its divisors is an integer number (170482788).

Almost surely, 2^644046071 is an apocalyptic number.

644046071 is a deficient number, since it is larger than the sum of its proper divisors (37885081).

644046071 is a wasteful number, since it uses less digits than its factorization.

644046071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37885080.

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 644046071 is about 25378.0627905284. The cubic root of 644046071 is about 863.5861031780.

The spelling of 644046071 in words is "six hundred forty-four million, forty-six thousand, seventy-one".