645643808040 has 384 divisors, whose sum is σ = 2489772257280. Its totient is φ = 131038871040.

The previous prime is 645643808011. The next prime is 645643808057. The reversal of 645643808040 is 40808346546.

645643808040 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4296657 + ... + 4444383.

It is an arithmetic number, because the mean of its divisors is an integer number (6483781920).

Almost surely, 2^645643808040 is an apocalyptic number.

645643808040 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 645643808040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1244886128640).

645643808040 is an abundant number, since it is smaller than the sum of its proper divisors (1844128449240).

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

645643808040 is a wasteful number, since it uses less digits than its factorization.

645643808040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147813 (or 147798 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 48.

The spelling of 645643808040 in words is "six hundred forty-five billion, six hundred forty-three million, eight hundred eight thousand, forty".