823136637809 has 4 divisors (see below), whose sum is σ = 845383574004. Its totient is φ = 800889701616.

The previous prime is 823136637767. The next prime is 823136637821. The reversal of 823136637809 is 908736631328.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 374578272784 + 448558365025 = 612028^2 + 669745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-823136637809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (823136637409) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11123468042 + ... + 11123468115.

It is an arithmetic number, because the mean of its divisors is an integer number (211345893501).

Almost surely, 2^823136637809 is an apocalyptic number.

It is an amenable number.

823136637809 is a deficient number, since it is larger than the sum of its proper divisors (22246936195).

823136637809 is a wasteful number, since it uses less digits than its factorization.

823136637809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22246936194.

The product of its (nonzero) digits is 7838208, while the sum is 56.

The spelling of 823136637809 in words is "eight hundred twenty-three billion, one hundred thirty-six million, six hundred thirty-seven thousand, eight hundred nine".