640531253 has 4 divisors (see below), whose sum is σ = 678209580. Its totient is φ = 602852928.

The previous prime is 640531201. The next prime is 640531259. The reversal of 640531253 is 352135046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 352135046 = 2 ⋅176067523.

It can be written as a sum of positive squares in 2 ways, for example, as 487217329 + 153313924 = 22073^2 + 12382^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640531253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640531259) 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 3 ways as a sum of consecutive naturals, for example, 18839138 + ... + 18839171.

It is an arithmetic number, because the mean of its divisors is an integer number (169552395).

Almost surely, 2^640531253 is an apocalyptic number.

It is an amenable number.

640531253 is a deficient number, since it is larger than the sum of its proper divisors (37678327).

640531253 is a wasteful number, since it uses less digits than its factorization.

640531253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37678326.

The product of its (nonzero) digits is 10800, while the sum is 29.

The square root of 640531253 is about 25308.7189126593. The cubic root of 640531253 is about 862.0122579602.

Adding to 640531253 its reverse (352135046), we get a palindrome (992666299).

The spelling of 640531253 in words is "six hundred forty million, five hundred thirty-one thousand, two hundred fifty-three".