823666 has 4 divisors (see below), whose sum is σ = 1235502. Its totient is φ = 411832.

The previous prime is 823663. The next prime is 823679. The reversal of 823666 is 666328.

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

It can be written as a sum of positive squares in only one way, i.e., 758641 + 65025 = 871^2 + 255^2 .

It is an Ulam number.

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 as a sum of consecutive naturals, namely, 205915 + ... + 205918.

2⁸²³⁶⁶⁶ is an apocalyptic number.

823666 is a deficient number, since it is larger than the sum of its proper divisors (411836).

823666 is a wasteful number, since it uses less digits than its factorization.

823666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 411835.

The product of its digits is 10368, while the sum is 31.

The square root of 823666 is about 907.5604663051. The cubic root of 823666 is about 93.7382942422.

The spelling of 823666 in words is "eight hundred twenty-three thousand, six hundred sixty-six".