644743686480 has 160 divisors (see below), whose sum is σ = 2057171142144. Its totient is φ = 166922477568.

The previous prime is 644743686479. The next prime is 644743686493. The reversal of 644743686480 is 84686347446.

It is a Harshad number since it is a multiple of its sum of digits (60).

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, 4033032 + ... + 4189848.

Almost surely, 2^644743686480 is an apocalyptic number.

644743686480 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 644743686480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1028585571072).

644743686480 is an abundant number, since it is smaller than the sum of its proper divisors (1412427455664).

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

644743686480 is a wasteful number, since it uses less digits than its factorization.

644743686480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157333 (or 157327 counting only the distinct ones).

The product of its (nonzero) digits is 74317824, while the sum is 60.

The spelling of 644743686480 in words is "six hundred forty-four billion, seven hundred forty-three million, six hundred eighty-six thousand, four hundred eighty".