640800250 has 24 divisors (see below), whose sum is σ = 1200327804. Its totient is φ = 256160000.

The previous prime is 640800241. The next prime is 640800253. The reversal of 640800250 is 52008046.

It can be written as a sum of positive squares in 6 ways, for example, as 402684489 + 238115761 = 20067^2 + 15431^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (640800253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 399450 + ... + 401050.

Almost surely, 2^640800250 is an apocalyptic number.

640800250 is a deficient number, since it is larger than the sum of its proper divisors (559527554).

640800250 is an frugal number, since it uses more digits than its factorization.

640800250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3219 (or 1608 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 640800250 is about 25314.0326696479. The cubic root of 640800250 is about 862.1329110681.

Adding to 640800250 its reverse (52008046), we get a palindrome (692808296).

The spelling of 640800250 in words is "six hundred forty million, eight hundred thousand, two hundred fifty".