640886400 has 864 divisors, whose sum is σ = 3028690080. Its totient is φ = 125337600.

The previous prime is 640886377. The next prime is 640886401. The reversal of 640886400 is 4688046.

640886400 is a `hidden beast` number, since 6 + 4 + 0 + 8 + 8 + 640 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640886401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 37699192 + ... + 37699208.

Almost surely, 2^640886400 is an apocalyptic number.

640886400 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 640886400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1514345040).

640886400 is an abundant number, since it is smaller than the sum of its proper divisors (2387803680).

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

640886400 is a wasteful number, since it uses less digits than its factorization.

640886400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 640886400 is about 25315.7342378213. The cubic root of 640886400 is about 862.1715447516.

The spelling of 640886400 in words is "six hundred forty million, eight hundred eighty-six thousand, four hundred".