643836253 has 4 divisors (see below), whose sum is σ = 644069728. Its totient is φ = 643602780.

The previous prime is 643836203. The next prime is 643836283. The reversal of 643836253 is 352638346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643836253 - 2⁹ = 643835741 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 (643836203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 112551 + ... + 118132.

It is an arithmetic number, because the mean of its divisors is an integer number (161017432).

Almost surely, 2^643836253 is an apocalyptic number.

It is an amenable number.

643836253 is a deficient number, since it is larger than the sum of its proper divisors (233475).

643836253 is a wasteful number, since it uses less digits than its factorization.

643836253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233474.

The product of its digits is 311040, while the sum is 40.

The square root of 643836253 is about 25373.9286079235. The cubic root of 643836253 is about 863.4923129988.

The spelling of 643836253 in words is "six hundred forty-three million, eight hundred thirty-six thousand, two hundred fifty-three".