221117823 has 16 divisors (see below), whose sum is σ = 338150400. Its totient is φ = 142656120.

The previous prime is 221117821. The next prime is 221117851. The reversal of 221117823 is 328711122.

It is not a de Polignac number, because 221117823 - 2¹ = 221117821 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221117821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131253 + ... + 132926.

It is an arithmetic number, because the mean of its divisors is an integer number (21134400).

Almost surely, 2^221117823 is an apocalyptic number.

221117823 is a deficient number, since it is larger than the sum of its proper divisors (117032577).

221117823 is a wasteful number, since it uses less digits than its factorization.

221117823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264219 (or 264213 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 221117823 is about 14870.0310356098. The cubic root of 221117823 is about 604.7017841347.

Adding to 221117823 its reverse (328711122), we get a palindrome (549828945).

The spelling of 221117823 in words is "two hundred twenty-one million, one hundred seventeen thousand, eight hundred twenty-three".