644123356 has 6 divisors (see below), whose sum is σ = 1127215880. Its totient is φ = 322061676.

The previous prime is 644123341. The next prime is 644123357. The reversal of 644123356 is 653321446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644123357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80515416 + ... + 80515423.

Almost surely, 2^644123356 is an apocalyptic number.

It is an amenable number.

644123356 is a deficient number, since it is larger than the sum of its proper divisors (483092524).

644123356 is a wasteful number, since it uses less digits than its factorization.

644123356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161030843 (or 161030841 counting only the distinct ones).

The product of its digits is 51840, while the sum is 34.

The square root of 644123356 is about 25379.5854182057. The cubic root of 644123356 is about 863.6206450043.

The spelling of 644123356 in words is "six hundred forty-four million, one hundred twenty-three thousand, three hundred fifty-six".