644226264 has 144 divisors (see below), whose sum is σ = 1979598600. Its totient is φ = 193976640.

The previous prime is 644226263. The next prime is 644226281. The reversal of 644226264 is 462622446.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

644226264 is a `hidden beast` number, since 6 + 4 + 4 + 22 + 626 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644226263) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4103274 + ... + 4103430.

Almost surely, 2^644226264 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644226264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (989799300).

644226264 is an abundant number, since it is smaller than the sum of its proper divisors (1335372336).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644226264 is a wasteful number, since it uses less digits than its factorization.

644226264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351 (or 173 counting only the distinct ones).

The product of its digits is 110592, while the sum is 36.

The square root of 644226264 is about 25381.6127147193. The cubic root of 644226264 is about 863.6666345082. Note that the first 4 decimals are identical.

The spelling of 644226264 in words is "six hundred forty-four million, two hundred twenty-six thousand, two hundred sixty-four".