221111001 has 12 divisors (see below), whose sum is σ = 328015012. Its totient is φ = 143423136.

The previous prime is 221110997. The next prime is 221111021. The reversal of 221111001 is 100111122.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 159896025 + 61214976 = 12645^2 + 7824^2 .

It is not a de Polignac number, because 221111001 - 2² = 221110997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221111021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 331666 + ... + 332331.

Almost surely, 2^221111001 is an apocalyptic number.

It is an amenable number.

221111001 is a deficient number, since it is larger than the sum of its proper divisors (106904011).

221111001 is a wasteful number, since it uses less digits than its factorization.

221111001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664040 (or 664037 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 221111001 is about 14869.8016462897. The cubic root of 221111001 is about 604.6955652511.

Adding to 221111001 its reverse (100111122), we get a palindrome (321222123).

The spelling of 221111001 in words is "two hundred twenty-one million, one hundred eleven thousand, one".