636786520661 has 2 divisors, whose sum is σ = 636786520662. Its totient is φ = 636786520660.

The previous prime is 636786520597. The next prime is 636786520663. The reversal of 636786520661 is 166025687636.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 632963448100 + 3823072561 = 795590^2 + 61831^2 .

It is a cyclic number.

It is not a de Polignac number, because 636786520661 - 2⁶ = 636786520597 is a prime.

Together with 636786520663, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 636786520597 and 636786520606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636786520663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318393260330 + 318393260331.

It is an arithmetic number, because the mean of its divisors is an integer number (318393260331).

Almost surely, 2^636786520661 is an apocalyptic number.

It is an amenable number.

636786520661 is a deficient number, since it is larger than the sum of its proper divisors (1).

636786520661 is an equidigital number, since it uses as much as digits as its factorization.

636786520661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13063680, while the sum is 56.

The spelling of 636786520661 in words is "six hundred thirty-six billion, seven hundred eighty-six million, five hundred twenty thousand, six hundred sixty-one".