1221217 has 4 divisors (see below), whose sum is σ = 1238020. Its totient is φ = 1204416.

The previous prime is 1221197. The next prime is 1221221. The reversal of 1221217 is 7121221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7121221 = 613 ⋅11617.

It can be written as a sum of positive squares in 2 ways, for example, as 746496 + 474721 = 864^2 + 689^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221217 - 2⁷ = 1221089 is a prime.

It is a super-2 number, since 2×1221217² = 2982741922178, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221217.

It is not an unprimeable number, because it can be changed into a prime (1221247) 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, 8292 + ... + 8437.

It is an arithmetic number, because the mean of its divisors is an integer number (309505).

2^1221217 is an apocalyptic number.

It is an amenable number.

1221217 is a deficient number, since it is larger than the sum of its proper divisors (16803).

1221217 is an equidigital number, since it uses as much as digits as its factorization.

1221217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16802.

The product of its digits is 56, while the sum is 16.

The square root of 1221217 is about 1105.0868744130. The cubic root of 1221217 is about 106.8884912805. Note that the first 3 decimals are identical.

Adding to 1221217 its reverse (7121221), we get a palindrome (8342438).

The spelling of 1221217 in words is "one million, two hundred twenty-one thousand, two hundred seventeen".