1221202121 has 4 divisors (see below), whose sum is σ = 1221634512. Its totient is φ = 1220769732.

The previous prime is 1221202091. The next prime is 1221202133. The reversal of 1221202121 is 1212021221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221202121 - 2¹⁰ = 1221201097 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 = 1221202096 and 1221202105.

It is not an unprimeable number, because it can be changed into a prime (1221202321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 211931 + ... + 217616.

It is an arithmetic number, because the mean of its divisors is an integer number (305408628).

Almost surely, 2^1221202121 is an apocalyptic number.

It is an amenable number.

1221202121 is a deficient number, since it is larger than the sum of its proper divisors (432391).

1221202121 is an equidigital number, since it uses as much as digits as its factorization.

1221202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 432390.

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

The square root of 1221202121 is about 34945.7024682578. The cubic root of 1221202121 is about 1068.8805717789.

Adding to 1221202121 its reverse (1212021221), we get a palindrome (2433223342).

Subtracting from 1221202121 its reverse (1212021221), we obtain a square (9180900 = 3030²).

It can be divided in two parts, 1 and 221202121, that added together give a palindrome (221202122).

The spelling of 1221202121 in words is "one billion, two hundred twenty-one million, two hundred two thousand, one hundred twenty-one".