1220211221 has 4 divisors (see below), whose sum is σ = 1262287500. Its totient is φ = 1178134944.

The previous prime is 1220211211. The next prime is 1220211229. The reversal of 1220211221 is 1221120221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1221120221 = 1493 ⋅817897.

It can be written as a sum of positive squares in 2 ways, for example, as 1012130596 + 208080625 = 31814^2 + 14425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1220211221 - 2²² = 1216016917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1220211196 and 1220211205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220211229) 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, 21038096 + ... + 21038153.

It is an arithmetic number, because the mean of its divisors is an integer number (315571875).

Almost surely, 2^1220211221 is an apocalyptic number.

It is an amenable number.

1220211221 is a deficient number, since it is larger than the sum of its proper divisors (42076279).

1220211221 is an equidigital number, since it uses as much as digits as its factorization.

1220211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42076278.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1220211221 is about 34931.5218821053. The cubic root of 1220211221 is about 1068.5913921419.

Adding to 1220211221 its reverse (1221120221), we get a palindrome (2441331442).

The spelling of 1220211221 in words is "one billion, two hundred twenty million, two hundred eleven thousand, two hundred twenty-one".