640244400 has 120 divisors (see below), whose sum is σ = 2085908160. Its totient is φ = 167819520.

The previous prime is 640244369. The next prime is 640244431. The reversal of 640244400 is 4442046.

It is an interprime number because it is at equal distance from previous prime (640244369) and next prime (640244431).

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-3 number, since 3×640244400³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66279 + ... + 75321.

It is an arithmetic number, because the mean of its divisors is an integer number (17382568).

Almost surely, 2^640244400 is an apocalyptic number.

640244400 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 640244400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1042954080).

640244400 is an abundant number, since it is smaller than the sum of its proper divisors (1445663760).

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

640244400 is a wasteful number, since it uses less digits than its factorization.

640244400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9123 (or 9112 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 24.

The square root of 640244400 is about 25303.0511994107. The cubic root of 640244400 is about 861.8835586852.

Adding to 640244400 its reverse (4442046), we get a palindrome (644686446).

The spelling of 640244400 in words is "six hundred forty million, two hundred forty-four thousand, four hundred".