111661221 has 16 divisors (see below), whose sum is σ = 170331264. Its totient is φ = 63738624.

The previous prime is 111661213. The next prime is 111661267. The reversal of 111661221 is 122166111.

It is not a de Polignac number, because 111661221 - 2³ = 111661213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111661211) 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, 22825 + ... + 27281.

It is an arithmetic number, because the mean of its divisors is an integer number (10645704).

Almost surely, 2^111661221 is an apocalyptic number.

It is an amenable number.

111661221 is a deficient number, since it is larger than the sum of its proper divisors (58670043).

111661221 is a wasteful number, since it uses less digits than its factorization.

111661221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5660.

The product of its digits is 144, while the sum is 21.

The square root of 111661221 is about 10566.9873190044. The cubic root of 111661221 is about 481.5419467451.

The spelling of 111661221 in words is "one hundred eleven million, six hundred sixty-one thousand, two hundred twenty-one".