636479561 has 2 divisors, whose sum is σ = 636479562. Its totient is φ = 636479560.

The previous prime is 636479533. The next prime is 636479563. The reversal of 636479561 is 165974636.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 518973961 + 117505600 = 22781^2 + 10840^2 .

It is a cyclic number.

It is not a de Polignac number, because 636479561 - 2⁶ = 636479497 is a prime.

It is a Sophie Germain prime.

Together with 636479563, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (636479563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318239780 + 318239781.

It is an arithmetic number, because the mean of its divisors is an integer number (318239781).

Almost surely, 2^636479561 is an apocalyptic number.

It is an amenable number.

636479561 is a deficient number, since it is larger than the sum of its proper divisors (1).

636479561 is an equidigital number, since it uses as much as digits as its factorization.

636479561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 816480, while the sum is 47.

The square root of 636479561 is about 25228.5465494943. The cubic root of 636479561 is about 860.1908540724.

The spelling of 636479561 in words is "six hundred thirty-six million, four hundred seventy-nine thousand, five hundred sixty-one".