640501400 has 288 divisors, whose sum is σ = 1979040000. Its totient is φ = 188179200.

The previous prime is 640501391. The next prime is 640501423. The reversal of 640501400 is 4105046.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

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 71 ways as a sum of consecutive naturals, for example, 3218501 + ... + 3218699.

Almost surely, 2^640501400 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 640501400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (989520000).

640501400 is an abundant number, since it is smaller than the sum of its proper divisors (1338538600).

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

640501400 is a wasteful number, since it uses less digits than its factorization.

640501400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263 (or 243 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 640501400 is about 25308.1291287997. The cubic root of 640501400 is about 861.9988659248.

Adding to 640501400 its reverse (4105046), we get a palindrome (644606446).

The spelling of 640501400 in words is "six hundred forty million, five hundred one thousand, four hundred".