823115387561 has 4 divisors (see below), whose sum is σ = 823178508432. Its totient is φ = 823052266692.

The previous prime is 823115387551. The next prime is 823115387579. The reversal of 823115387561 is 165783511328.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 823115387561 - 2¹⁰ = 823115386537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (823115387531) 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, 31540871 + ... + 31566956.

It is an arithmetic number, because the mean of its divisors is an integer number (205794627108).

Almost surely, 2^823115387561 is an apocalyptic number.

It is an amenable number.

823115387561 is a deficient number, since it is larger than the sum of its proper divisors (63120871).

823115387561 is a wasteful number, since it uses less digits than its factorization.

823115387561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63120870.

The product of its digits is 1209600, while the sum is 50.

Adding to 823115387561 its reverse (165783511328), we get a palindrome (988898898889).

The spelling of 823115387561 in words is "eight hundred twenty-three billion, one hundred fifteen million, three hundred eighty-seven thousand, five hundred sixty-one".