644232169440 has 192 divisors, whose sum is σ = 2256349435200. Its totient is φ = 171678154752.

The previous prime is 644232169409. The next prime is 644232169487. The reversal of 644232169440 is 44961232446.

644232169440 is a `hidden beast` number, since 6 + 4 + 42 + 3 + 2 + 169 + 440 = 666.

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 31 ways as a sum of consecutive naturals, for example, 6382404 + ... + 6482556.

It is an arithmetic number, because the mean of its divisors is an integer number (11751819975).

Almost surely, 2^644232169440 is an apocalyptic number.

644232169440 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 644232169440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1128174717600).

644232169440 is an abundant number, since it is smaller than the sum of its proper divisors (1612117265760).

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

644232169440 is a wasteful number, since it uses less digits than its factorization.

644232169440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101666 (or 101652 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 45.

The spelling of 644232169440 in words is "six hundred forty-four billion, two hundred thirty-two million, one hundred sixty-nine thousand, four hundred forty".