811649638991 has 2 divisors, whose sum is σ = 811649638992. Its totient is φ = 811649638990.

The previous prime is 811649638963. The next prime is 811649639063. The reversal of 811649638991 is 199836946118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 811649638991 - 2³⁰ = 810575897167 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (811649638091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405824819495 + 405824819496.

It is an arithmetic number, because the mean of its divisors is an integer number (405824819496).

Almost surely, 2^811649638991 is an apocalyptic number.

811649638991 is a deficient number, since it is larger than the sum of its proper divisors (1).

811649638991 is an equidigital number, since it uses as much as digits as its factorization.

811649638991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20155392, while the sum is 65.

Adding to 811649638991 its sum of digits (65), we get a square (811649639056 = 900916²).

The spelling of 811649638991 in words is "eight hundred eleven billion, six hundred forty-nine million, six hundred thirty-eight thousand, nine hundred ninety-one".