644138234 has 4 divisors (see below), whose sum is σ = 966207354. Its totient is φ = 322069116.

The previous prime is 644138213. The next prime is 644138303. The reversal of 644138234 is 432831446.

644138234 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, and also an emirpimes, since its reverse is a distinct semiprime: 432831446 = 2 ⋅216415723.

It can be written as a sum of positive squares in only one way, i.e., 325694209 + 318444025 = 18047^2 + 17845^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644138194 and 644138203.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161034557 + ... + 161034560.

Almost surely, 2^644138234 is an apocalyptic number.

644138234 is a deficient number, since it is larger than the sum of its proper divisors (322069120).

644138234 is a wasteful number, since it uses less digits than its factorization.

644138234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322069119.

The product of its digits is 55296, while the sum is 35.

The square root of 644138234 is about 25379.8785261080. The cubic root of 644138234 is about 863.6272942736.

The spelling of 644138234 in words is "six hundred forty-four million, one hundred thirty-eight thousand, two hundred thirty-four".