636420391 has 2 divisors, whose sum is σ = 636420392. Its totient is φ = 636420390.

The previous prime is 636420377. The next prime is 636420437. The reversal of 636420391 is 193024636.

It is a happy number.

636420391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 636420391 - 2⁷ = 636420263 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636420311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318210195 + 318210196.

It is an arithmetic number, because the mean of its divisors is an integer number (318210196).

Almost surely, 2^636420391 is an apocalyptic number.

636420391 is a deficient number, since it is larger than the sum of its proper divisors (1).

636420391 is an equidigital number, since it uses as much as digits as its factorization.

636420391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 34.

The square root of 636420391 is about 25227.3738427130. The cubic root of 636420391 is about 860.1641975107.

The spelling of 636420391 in words is "six hundred thirty-six million, four hundred twenty thousand, three hundred ninety-one".