823866661 has 4 divisors (see below), whose sum is σ = 824432800. Its totient is φ = 823300524.

The previous prime is 823866607. The next prime is 823866689. The reversal of 823866661 is 166668328.

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 823866661 - 2²⁹ = 286995749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (823866691) 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, 280881 + ... + 283798.

It is an arithmetic number, because the mean of its divisors is an integer number (206108200).

Almost surely, 2^823866661 is an apocalyptic number.

It is an amenable number.

823866661 is a deficient number, since it is larger than the sum of its proper divisors (566139).

823866661 is a wasteful number, since it uses less digits than its factorization.

823866661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566138.

The product of its digits is 497664, while the sum is 46.

The square root of 823866661 is about 28703.0775527643. The cubic root of 823866661 is about 937.4590577913.

The spelling of 823866661 in words is "eight hundred twenty-three million, eight hundred sixty-six thousand, six hundred sixty-one".