643828697 has 2 divisors, whose sum is σ = 643828698. Its totient is φ = 643828696.

The previous prime is 643828663. The next prime is 643828711. The reversal of 643828697 is 796828346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 498360976 + 145467721 = 22324^2 + 12061^2 .

It is a cyclic number.

It is not a de Polignac number, because 643828697 - 2⁸ = 643828441 is a prime.

It is not a weakly prime, because it can be changed into another prime (643828657) 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 as a sum of consecutive naturals, namely, 321914348 + 321914349.

It is an arithmetic number, because the mean of its divisors is an integer number (321914349).

Almost surely, 2^643828697 is an apocalyptic number.

It is an amenable number.

643828697 is a deficient number, since it is larger than the sum of its proper divisors (1).

643828697 is an equidigital number, since it uses as much as digits as its factorization.

643828697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3483648, while the sum is 53.

The square root of 643828697 is about 25373.7797145006. The cubic root of 643828697 is about 863.4889350315.

The spelling of 643828697 in words is "six hundred forty-three million, eight hundred twenty-eight thousand, six hundred ninety-seven".