221511121 has 8 divisors (see below), whose sum is σ = 241232040. Its totient is φ = 202173312.

The previous prime is 221511113. The next prime is 221511133. The reversal of 221511121 is 121115122.

It can be written as a sum of positive squares in 4 ways, for example, as 29550096 + 191961025 = 5436^2 + 13855^2 .

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 221511121 - 2³ = 221511113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221511095 and 221511104.

It is not an unprimeable number, because it can be changed into a prime (221511421) 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, 94570 + ... + 96883.

It is an arithmetic number, because the mean of its divisors is an integer number (30154005).

Almost surely, 2^221511121 is an apocalyptic number.

It is an amenable number.

221511121 is a deficient number, since it is larger than the sum of its proper divisors (19720919).

221511121 is a wasteful number, since it uses less digits than its factorization.

221511121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191555.

The product of its digits is 40, while the sum is 16.

The square root of 221511121 is about 14883.2496787496. The cubic root of 221511121 is about 605.0600955718.

Adding to 221511121 its reverse (121115122), we get a palindrome (342626243).

The spelling of 221511121 in words is "two hundred twenty-one million, five hundred eleven thousand, one hundred twenty-one".