636409 has 2 divisors, whose sum is σ = 636410. Its totient is φ = 636408.

The previous prime is 636407. The next prime is 636421. The reversal of 636409 is 904636.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 558009 + 78400 = 747^2 + 280^2 .

It is a cyclic number.

It is not a de Polignac number, because 636409 - 2¹ = 636407 is a prime.

Together with 636407, it forms a pair of twin primes.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (636403) 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, 318204 + 318205.

It is an arithmetic number, because the mean of its divisors is an integer number (318205).

2⁶³⁶⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

636409 is a deficient number, since it is larger than the sum of its proper divisors (1).

636409 is an equidigital number, since it uses as much as digits as its factorization.

636409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 636409 is about 797.7524678746. The cubic root of 636409 is about 86.0159065584.

The spelling of 636409 in words is "six hundred thirty-six thousand, four hundred nine".