640345253 has 2 divisors, whose sum is σ = 640345254. Its totient is φ = 640345252.

The previous prime is 640345241. The next prime is 640345283. The reversal of 640345253 is 352543046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 639938209 + 407044 = 25297^2 + 638^2 .

It is a cyclic number.

It is not a de Polignac number, because 640345253 - 2⁸ = 640344997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640345213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320172626 + 320172627.

It is an arithmetic number, because the mean of its divisors is an integer number (320172627).

Almost surely, 2^640345253 is an apocalyptic number.

It is an amenable number.

640345253 is a deficient number, since it is larger than the sum of its proper divisors (1).

640345253 is an equidigital number, since it uses as much as digits as its factorization.

640345253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 32.

The square root of 640345253 is about 25305.0440228821. The cubic root of 640345253 is about 861.9288117057.

Adding to 640345253 its reverse (352543046), we get a palindrome (992888299).

The spelling of 640345253 in words is "six hundred forty million, three hundred forty-five thousand, two hundred fifty-three".