636123641 has 2 divisors, whose sum is σ = 636123642. Its totient is φ = 636123640.

The previous prime is 636123617. The next prime is 636123643. The reversal of 636123641 is 146321636.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 558613225 + 77510416 = 23635^2 + 8804^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-636123641 is a prime.

It is a Sophie Germain prime.

Together with 636123643, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 636123598 and 636123607.

It is not a weakly prime, because it can be changed into another prime (636123643) 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, 318061820 + 318061821.

It is an arithmetic number, because the mean of its divisors is an integer number (318061821).

Almost surely, 2^636123641 is an apocalyptic number.

It is an amenable number.

636123641 is a deficient number, since it is larger than the sum of its proper divisors (1).

636123641 is an equidigital number, since it uses as much as digits as its factorization.

636123641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 32.

The square root of 636123641 is about 25221.4916489886. The cubic root of 636123641 is about 860.0304843169.

The spelling of 636123641 in words is "six hundred thirty-six million, one hundred twenty-three thousand, six hundred forty-one".