635891 has 2 divisors, whose sum is σ = 635892. Its totient is φ = 635890.

The previous prime is 635879. The next prime is 635893. The reversal of 635891 is 198536.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-635891 is a prime.

Together with 635893, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (635893) 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, 317945 + 317946.

It is an arithmetic number, because the mean of its divisors is an integer number (317946).

2⁶³⁵⁸⁹¹ is an apocalyptic number.

635891 is a deficient number, since it is larger than the sum of its proper divisors (1).

635891 is an equidigital number, since it uses as much as digits as its factorization.

635891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 32.

The square root of 635891 is about 797.4277396730. The cubic root of 635891 is about 85.9925629047.

The spelling of 635891 in words is "six hundred thirty-five thousand, eight hundred ninety-one".