121221 has 6 divisors (see below), whose sum is σ = 175110.
Its totient is φ = 80808.
The previous prime is 121189. The next prime is 121229. The reversal of 121221 is 122121.
Adding to 121221 its reverse (122121), we get a palindrome (243342).
Subtracting 121221 from its reverse (122121), we obtain a square (900 = 302).
It can be divided in two parts, 1212 and 21, that multiplied together give a palindrome (25452).
It can be written as a sum of positive squares in only one way, i.e., 108900 + 12321 = 330^2 + 111^2
It is not a de Polignac number, because 121221 - 25 = 121189 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 13469 = 121221 / (1 + 2 + 1 + 2 + 2 + 1).
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (121229) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6726 + ... + 6743.
It is an arithmetic number, because the mean of its divisors is an integer number (29185).
2121221 is an apocalyptic number.
It is an amenable number.
121221 is a deficient number, since it is larger than the sum of its proper divisors (53889).
121221 is a wasteful number, since it uses less digits than its factorization.
121221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 13475 (or 13472 counting only the distinct ones).
The product of its digits is 8, while the sum is 9.
The square root of 121221 is about 348.1680628662.
The cubic root of 121221 is about 49.4909686615.
The spelling of 121221 in words is "one hundred twenty-one thousand, two hundred twenty-one", and thus it is an iban number.