645759644544 has 384 divisors, whose sum is σ = 2247466816800. Its totient is φ = 181971836928.

The previous prime is 645759644503. The next prime is 645759644557. The reversal of 645759644544 is 445446957546.

645759644544 is a `hidden beast` number, since 6 + 4 + 575 + 9 + 6 + 4 + 4 + 54 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12335994 + ... + 12388230.

Almost surely, 2^645759644544 is an apocalyptic number.

645759644544 is a gapful number since it is divisible by the number (64) 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 645759644544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1123733408400).

645759644544 is an abundant number, since it is smaller than the sum of its proper divisors (1601707172256).

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

645759644544 is a wasteful number, since it uses less digits than its factorization.

645759644544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52347 (or 52322 counting only the distinct ones).

The product of its digits is 290304000, while the sum is 63.

The spelling of 645759644544 in words is "six hundred forty-five billion, seven hundred fifty-nine million, six hundred forty-four thousand, five hundred forty-four".