640347206400 has 864 divisors, whose sum is σ = 2581297286400. Its totient is φ = 154039910400.

The previous prime is 640347206399. The next prime is 640347206413. The reversal of 640347206400 is 4602743046.

640347206400 is a `hidden beast` number, since 6 + 4 + 0 + 3 + 4 + 7 + 2 + 0 + 640 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 260408371 + ... + 260410829.

It is an arithmetic number, because the mean of its divisors is an integer number (2987612600).

Almost surely, 2^640347206400 is an apocalyptic number.

640347206400 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 640347206400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1290648643200).

640347206400 is an abundant number, since it is smaller than the sum of its proper divisors (1940950080000).

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

640347206400 is a wasteful number, since it uses less digits than its factorization.

640347206400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2642 (or 2617 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 36.

Adding to 640347206400 its reverse (4602743046), we get a palindrome (644949949446).

The spelling of 640347206400 in words is "six hundred forty billion, three hundred forty-seven million, two hundred six thousand, four hundred".