645906253 has 2 divisors, whose sum is σ = 645906254. Its totient is φ = 645906252.

The previous prime is 645906227. The next prime is 645906257. The reversal of 645906253 is 352609546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 350513284 + 295392969 = 18722^2 + 17187^2 .

It is a cyclic number.

It is not a de Polignac number, because 645906253 - 2¹⁷ = 645775181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645906257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322953126 + 322953127.

It is an arithmetic number, because the mean of its divisors is an integer number (322953127).

Almost surely, 2^645906253 is an apocalyptic number.

It is an amenable number.

645906253 is a deficient number, since it is larger than the sum of its proper divisors (1).

645906253 is an equidigital number, since it uses as much as digits as its factorization.

645906253 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 194400, while the sum is 40.

The square root of 645906253 is about 25414.6857741740. The cubic root of 645906253 is about 864.4167286423.

The spelling of 645906253 in words is "six hundred forty-five million, nine hundred six thousand, two hundred fifty-three".