643257851 has 2 divisors, whose sum is σ = 643257852. Its totient is φ = 643257850.

The previous prime is 643257847. The next prime is 643257869. The reversal of 643257851 is 158752346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643257851 - 2² = 643257847 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643257799 and 643257808.

It is not a weakly prime, because it can be changed into another prime (643257551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321628925 + 321628926.

It is an arithmetic number, because the mean of its divisors is an integer number (321628926).

Almost surely, 2^643257851 is an apocalyptic number.

643257851 is a deficient number, since it is larger than the sum of its proper divisors (1).

643257851 is an equidigital number, since it uses as much as digits as its factorization.

643257851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 201600, while the sum is 41.

The square root of 643257851 is about 25362.5284819949. The cubic root of 643257851 is about 863.2336575227.

The spelling of 643257851 in words is "six hundred forty-three million, two hundred fifty-seven thousand, eight hundred fifty-one".