644443845 has 16 divisors (see below), whose sum is σ = 1031933952. Its totient is φ = 343428800.

The previous prime is 644443823. The next prime is 644443867. The reversal of 644443845 is 548344446.

It is an interprime number because it is at equal distance from previous prime (644443823) and next prime (644443867).

It is not a de Polignac number, because 644443845 - 2⁹ = 644443333 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644443797 and 644443806.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3004 + ... + 36026.

It is an arithmetic number, because the mean of its divisors is an integer number (64495872).

Almost surely, 2^644443845 is an apocalyptic number.

It is an amenable number.

644443845 is a deficient number, since it is larger than the sum of its proper divisors (387490107).

644443845 is a wasteful number, since it uses less digits than its factorization.

644443845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34332.

The product of its digits is 737280, while the sum is 42.

The square root of 644443845 is about 25385.8985462402. The cubic root of 644443845 is about 863.7638551633.

The spelling of 644443845 in words is "six hundred forty-four million, four hundred forty-three thousand, eight hundred forty-five".