64400020531640 has 128 divisors (see below), whose sum is σ = 156439670630400. Its totient is φ = 23786424076800.

The previous prime is 64400020531591. The next prime is 64400020531699. The reversal of 64400020531640 is 4613502000446.

It is a self number, because there is not a number n which added to its sum of digits gives 64400020531640.

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, 163912469 + ... + 164304891.

It is an arithmetic number, because the mean of its divisors is an integer number (1222184926800).

Almost surely, 2^{64400020531640} 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 64400020531640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78219835315200).

64400020531640 is an abundant number, since it is smaller than the sum of its proper divisors (92039650098760).

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

64400020531640 is a wasteful number, since it uses less digits than its factorization.

64400020531640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398637 (or 398633 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 35.

The spelling of 64400020531640 in words is "sixty-four trillion, four hundred billion, twenty million, five hundred thirty-one thousand, six hundred forty".