1221212243 has 4 divisors (see below), whose sum is σ = 1263323040. Its totient is φ = 1179101448.

The previous prime is 1221212219. The next prime is 1221212281. The reversal of 1221212243 is 3422121221.

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

It is a cyclic number.

It is not a de Polignac number, because 1221212243 - 2²² = 1217017939 is a prime.

It is a super-3 number, since 3×1221212243³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221212143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21055355 + ... + 21055412.

It is an arithmetic number, because the mean of its divisors is an integer number (315830760).

Almost surely, 2^1221212243 is an apocalyptic number.

1221212243 is a deficient number, since it is larger than the sum of its proper divisors (42110797).

1221212243 is an equidigital number, since it uses as much as digits as its factorization.

1221212243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42110796.

The product of its digits is 384, while the sum is 20.

The square root of 1221212243 is about 34945.8472926326. The cubic root of 1221212243 is about 1068.8835249290.

Adding to 1221212243 its reverse (3422121221), we get a palindrome (4643333464).

The spelling of 1221212243 in words is "one billion, two hundred twenty-one million, two hundred twelve thousand, two hundred forty-three".