823681 has 4 divisors (see below), whose sum is σ = 826672. Its totient is φ = 820692.

The previous prime is 823679. The next prime is 823703. The reversal of 823681 is 186328.

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 823681 - 2¹ = 823679 is a prime.

It is a super-2 number, since 2×823681² = 1356900779522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (823601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1035 + ... + 1648.

It is an arithmetic number, because the mean of its divisors is an integer number (206668).

2⁸²³⁶⁸¹ is an apocalyptic number.

It is an amenable number.

823681 is a deficient number, since it is larger than the sum of its proper divisors (2991).

823681 is a wasteful number, since it uses less digits than its factorization.

823681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2990.

The product of its digits is 2304, while the sum is 28.

The square root of 823681 is about 907.5687301797. The cubic root of 823681 is about 93.7388632697.

It can be divided in two parts, 82368 and 1, that added together give a square (82369 = 287²).

The spelling of 823681 in words is "eight hundred twenty-three thousand, six hundred eighty-one".