640542171744 has 144 divisors (see below), whose sum is σ = 1828490358240. Its totient is φ = 212701040640.

The previous prime is 640542171733. The next prime is 640542171767. The reversal of 640542171744 is 447171245046.

640542171744 is a `hidden beast` number, since 6 + 40 + 542 + 17 + 17 + 44 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a self number, because there is not a number n which added to its sum of digits gives 640542171744.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 100726837 + ... + 100733195.

It is an arithmetic number, because the mean of its divisors is an integer number (12697849710).

Almost surely, 2^640542171744 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 640542171744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (914245179120).

640542171744 is an abundant number, since it is smaller than the sum of its proper divisors (1187948186496).

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

640542171744 is a wasteful number, since it uses less digits than its factorization.

640542171744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7653 (or 7642 counting only the distinct ones).

The product of its (nonzero) digits is 752640, while the sum is 45.

The spelling of 640542171744 in words is "six hundred forty billion, five hundred forty-two million, one hundred seventy-one thousand, seven hundred forty-four".