221111111 has 8 divisors (see below), whose sum is σ = 241474464. Its totient is φ = 201227040.

The previous prime is 221111063. The next prime is 221111123. The reversal of 221111111 is 111111122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221111111 - 2⁶ = 221111047 is a prime.

It is a Duffinian number.

221111111 is a modest number, since divided by 11111 gives 2211 as remainder.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 221111092 and 221111101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221111131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 118856 + ... + 120701.

It is an arithmetic number, because the mean of its divisors is an integer number (30184308).

Almost surely, 2^221111111 is an apocalyptic number.

221111111 is a deficient number, since it is larger than the sum of its proper divisors (20363353).

221111111 is a wasteful number, since it uses less digits than its factorization.

221111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239641.

The product of its digits is 4, while the sum is 11.

The square root of 221111111 is about 14869.8053450608. The cubic root of 221111111 is about 604.6956655273.

Adding to 221111111 its sum of digits (11), we get a palindrome (221111122).

Adding to 221111111 its reverse (111111122), we get a palindrome (332222233).

It can be divided in two parts, 2211111 and 11, that added together give a palindrome (2211122).

The spelling of 221111111 in words is "two hundred twenty-one million, one hundred eleven thousand, one hundred eleven".