640425311 has 4 divisors (see below), whose sum is σ = 661084224. Its totient is φ = 619766400.

The previous prime is 640425307. The next prime is 640425319. The reversal of 640425311 is 113524046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640425311 - 2² = 640425307 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 (640425319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10329410 + ... + 10329471.

It is an arithmetic number, because the mean of its divisors is an integer number (165271056).

Almost surely, 2^640425311 is an apocalyptic number.

640425311 is a deficient number, since it is larger than the sum of its proper divisors (20658913).

640425311 is a wasteful number, since it uses less digits than its factorization.

640425311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20658912.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 640425311 is about 25306.6258319832. The cubic root of 640425311 is about 861.9647305692.

Adding to 640425311 its reverse (113524046), we get a palindrome (753949357).

The spelling of 640425311 in words is "six hundred forty million, four hundred twenty-five thousand, three hundred eleven".