18821233661 has 4 divisors (see below), whose sum is σ = 19639548192. Its totient is φ = 18002919132.

The previous prime is 18821233649. The next prime is 18821233663. The reversal of 18821233661 is 16633212881.

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 18821233661 - 2²² = 18817039357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18821233663) 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, 409157231 + ... + 409157276.

It is an arithmetic number, because the mean of its divisors is an integer number (4909887048).

Almost surely, 2^18821233661 is an apocalyptic number.

It is an amenable number.

18821233661 is a deficient number, since it is larger than the sum of its proper divisors (818314531).

18821233661 is an equidigital number, since it uses as much as digits as its factorization.

18821233661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 818314530.

The product of its digits is 82944, while the sum is 41.

The spelling of 18821233661 in words is "eighteen billion, eight hundred twenty-one million, two hundred thirty-three thousand, six hundred sixty-one".