823778867281 has 4 divisors (see below), whose sum is σ = 833034809700. Its totient is φ = 814522924864.

The previous prime is 823778867279. The next prime is 823778867287. The reversal of 823778867281 is 182768877328.

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 362036873025 + 461741994256 = 601695^2 + 679516^2 .

It is not a de Polignac number, because 823778867281 - 2¹ = 823778867279 is a prime.

It is a super-2 number, since 2×823778867281² (a number of 25 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (823778867287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4627971076 + ... + 4627971253.

It is an arithmetic number, because the mean of its divisors is an integer number (208258702425).

Almost surely, 2^823778867281 is an apocalyptic number.

It is an amenable number.

823778867281 is a deficient number, since it is larger than the sum of its proper divisors (9255942419).

823778867281 is an equidigital number, since it uses as much as digits as its factorization.

823778867281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9255942418.

The product of its digits is 101154816, while the sum is 67.

The spelling of 823778867281 in words is "eight hundred twenty-three billion, seven hundred seventy-eight million, eight hundred sixty-seven thousand, two hundred eighty-one".