20836839809 has 2 divisors, whose sum is σ = 20836839810. Its totient is φ = 20836839808.

The previous prime is 20836839797. The next prime is 20836839841. The reversal of 20836839809 is 90893863802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17683680400 + 3153159409 = 132980^2 + 56153^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20836839809 is a prime.

It is not a weakly prime, because it can be changed into another prime (20836839889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10418419904 + 10418419905.

It is an arithmetic number, because the mean of its divisors is an integer number (10418419905).

Almost surely, 2^20836839809 is an apocalyptic number.

It is an amenable number.

20836839809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20836839809 is an equidigital number, since it uses as much as digits as its factorization.

20836839809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4478976, while the sum is 56.

The spelling of 20836839809 in words is "twenty billion, eight hundred thirty-six million, eight hundred thirty-nine thousand, eight hundred nine".