644193648000 has 1280 divisors, whose sum is σ = 2895883436160. Its totient is φ = 138549657600.

The previous prime is 644193647987. The next prime is 644193648019. The reversal of 644193648000 is 846391446.

It is a super-2 number, since 2×644193648000² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 154221912 + ... + 154226088.

Almost surely, 2^644193648000 is an apocalyptic number.

644193648000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644193648000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1447941718080).

644193648000 is an abundant number, since it is smaller than the sum of its proper divisors (2251689788160).

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

644193648000 is a wasteful number, since it uses less digits than its factorization.

644193648000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4242 (or 4211 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 45.

The spelling of 644193648000 in words is "six hundred forty-four billion, one hundred ninety-three million, six hundred forty-eight thousand".