640402868736 has 640 divisors, whose sum is σ = 2087352115200. Its totient is φ = 195507302400.

The previous prime is 640402868731. The next prime is 640402868741. The reversal of 640402868736 is 637868204046.

It is an interprime number because it is at equal distance from previous prime (640402868731) and next prime (640402868741).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (640402868731) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 659528731 + ... + 659529701.

It is an arithmetic number, because the mean of its divisors is an integer number (3261487680).

Almost surely, 2^640402868736 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 640402868736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1043676057600).

640402868736 is an abundant number, since it is smaller than the sum of its proper divisors (1446949246464).

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

640402868736 is an frugal number, since it uses more digits than its factorization.

640402868736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060 (or 1026 counting only the distinct ones).

The product of its (nonzero) digits is 9289728, while the sum is 54.

The spelling of 640402868736 in words is "six hundred forty billion, four hundred two million, eight hundred sixty-eight thousand, seven hundred thirty-six".