823661 has 4 divisors (see below), whose sum is σ = 828000. Its totient is φ = 819324.

The previous prime is 823651. The next prime is 823663. The reversal of 823661 is 166328.

823661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a de Polignac number, because none of the positive numbers 2^k-823661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 823661.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 823661.

It is not an unprimeable number, because it can be changed into a prime (823663) 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, 1871 + ... + 2268.

It is an arithmetic number, because the mean of its divisors is an integer number (207000).

2⁸²³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

823661 is a deficient number, since it is larger than the sum of its proper divisors (4339).

823661 is a wasteful number, since it uses less digits than its factorization.

823661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4338.

The product of its digits is 1728, while the sum is 26.

The square root of 823661 is about 907.5577116636. The cubic root of 823661 is about 93.7381045648.

Adding to 823661 its reverse (166328), we get a palindrome (989989).

The spelling of 823661 in words is "eight hundred twenty-three thousand, six hundred sixty-one".