221991233 has 4 divisors (see below), whose sum is σ = 224189268. Its totient is φ = 219793200.

The previous prime is 221991221. The next prime is 221991247. The reversal of 221991233 is 332199122.

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

It can be written as a sum of positive squares in 2 ways, for example, as 192321424 + 29669809 = 13868^2 + 5447^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221991233 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 221991233.

It is not an unprimeable number, because it can be changed into a prime (221991283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1098866 + ... + 1099067.

It is an arithmetic number, because the mean of its divisors is an integer number (56047317).

Almost surely, 2^221991233 is an apocalyptic number.

It is an amenable number.

221991233 is a deficient number, since it is larger than the sum of its proper divisors (2198035).

221991233 is a wasteful number, since it uses less digits than its factorization.

221991233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2198034.

The product of its digits is 5832, while the sum is 32.

The square root of 221991233 is about 14899.3702215899. The cubic root of 221991233 is about 605.4969238834.

It can be divided in two parts, 22199 and 1233, that added together give a palindrome (23432).

The spelling of 221991233 in words is "two hundred twenty-one million, nine hundred ninety-one thousand, two hundred thirty-three".