644150664 has 128 divisors (see below), whose sum is σ = 1845043200. Its totient is φ = 208111680.

The previous prime is 644150641. The next prime is 644150677. The reversal of 644150664 is 466051446.

644150664 is a `hidden beast` number, since 644 + 1 + 5 + 0 + 6 + 6 + 4 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2071069 + ... + 2071379.

It is an arithmetic number, because the mean of its divisors is an integer number (14414400).

Almost surely, 2^644150664 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 644150664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (922521600).

644150664 is an abundant number, since it is smaller than the sum of its proper divisors (1200892536).

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

644150664 is a wasteful number, since it uses less digits than its factorization.

644150664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 592 (or 582 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The square root of 644150664 is about 25380.1234039553. The cubic root of 644150664 is about 863.6328494053.

The spelling of 644150664 in words is "six hundred forty-four million, one hundred fifty thousand, six hundred sixty-four".