1221281 has 4 divisors (see below), whose sum is σ = 1241364. Its totient is φ = 1201200.

The previous prime is 1221251. The next prime is 1221289. The reversal of 1221281 is 1821221.

It is a happy number.

1221281 is nontrivially palindromic in base 4.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46225 + 1175056 = 215^2 + 1084^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221281 - 2¹⁰ = 1220257 is a prime.

It is a super-2 number, since 2×1221281² = 2983054561922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221289) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9950 + ... + 10071.

It is an arithmetic number, because the mean of its divisors is an integer number (310341).

2^1221281 is an apocalyptic number.

It is an amenable number.

1221281 is a deficient number, since it is larger than the sum of its proper divisors (20083).

1221281 is an equidigital number, since it uses as much as digits as its factorization.

1221281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20082.

The product of its digits is 64, while the sum is 17.

The square root of 1221281 is about 1105.1158310331. The cubic root of 1221281 is about 106.8903584736.

The spelling of 1221281 in words is "one million, two hundred twenty-one thousand, two hundred eighty-one".