1212212221 has 4 divisors (see below), whose sum is σ = 1322413344. Its totient is φ = 1102011100.

The previous prime is 1212212219. The next prime is 1212212233. The reversal of 1212212221 is 1222122121.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1222122121 = 11 ⋅111102011.

It is a cyclic number.

It is not a de Polignac number, because 1212212221 - 2¹ = 1212212219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1212212195 and 1212212204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212212291) 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, 55100545 + ... + 55100566.

It is an arithmetic number, because the mean of its divisors is an integer number (330603336).

Almost surely, 2^1212212221 is an apocalyptic number.

1212212221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1212212221 is a deficient number, since it is larger than the sum of its proper divisors (110201123).

1212212221 is a wasteful number, since it uses less digits than its factorization.

1212212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110201122.

The product of its digits is 64, while the sum is 16.

The square root of 1212212221 is about 34816.8381821210. The cubic root of 1212212221 is about 1066.2512484667.

Adding to 1212212221 its reverse (1222122121), we get a palindrome (2434334342).

The spelling of 1212212221 in words is "one billion, two hundred twelve million, two hundred twelve thousand, two hundred twenty-one".