643085251 has 4 divisors (see below), whose sum is σ = 651894712. Its totient is φ = 634275792.

The previous prime is 643085243. The next prime is 643085263. The reversal of 643085251 is 152580346.

643085251 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 152580346 = 2 ⋅76290173.

It is a cyclic number.

It is not a de Polignac number, because 643085251 - 2³ = 643085243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643085291) 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, 4404621 + ... + 4404766.

It is an arithmetic number, because the mean of its divisors is an integer number (162973678).

Almost surely, 2^643085251 is an apocalyptic number.

643085251 is a deficient number, since it is larger than the sum of its proper divisors (8809461).

643085251 is an equidigital number, since it uses as much as digits as its factorization.

643085251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8809460.

The product of its (nonzero) digits is 28800, while the sum is 34.

The square root of 643085251 is about 25359.1255961242. The cubic root of 643085251 is about 863.1564425266.

The spelling of 643085251 in words is "six hundred forty-three million, eighty-five thousand, two hundred fifty-one".