640731600 has 240 divisors, whose sum is σ = 2337767040. Its totient is φ = 166579200.

The previous prime is 640731571. The next prime is 640731607. The reversal of 640731600 is 6137046.

640731600 is a `hidden beast` number, since 640 + 7 + 3 + 16 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640731607) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 442077 + ... + 443523.

It is an arithmetic number, because the mean of its divisors is an integer number (9740696).

Almost surely, 2^640731600 is an apocalyptic number.

640731600 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 640731600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1168883520).

640731600 is an abundant number, since it is smaller than the sum of its proper divisors (1697035440).

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

640731600 is a wasteful number, since it uses less digits than its factorization.

640731600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1515 (or 1498 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 640731600 is about 25312.6766660502. The cubic root of 640731600 is about 862.1021227228.

Adding to 640731600 its reverse (6137046), we get a palindrome (646868646).

The spelling of 640731600 in words is "six hundred forty million, seven hundred thirty-one thousand, six hundred".