1221222121 has 4 divisors (see below), whose sum is σ = 1395682432. Its totient is φ = 1046761812.

The previous prime is 1221222113. The next prime is 1221222127. The reversal of 1221222121 is 1212221221.

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.

It is a cyclic number.

It is not a de Polignac number, because 1221222121 - 2³ = 1221222113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221222095 and 1221222104.

It is not an unprimeable number, because it can be changed into a prime (1221222127) 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, 87230145 + ... + 87230158.

It is an arithmetic number, because the mean of its divisors is an integer number (348920608).

Almost surely, 2^1221222121 is an apocalyptic number.

It is an amenable number.

1221222121 is a deficient number, since it is larger than the sum of its proper divisors (174460311).

1221222121 is an equidigital number, since it uses as much as digits as its factorization.

1221222121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174460310.

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

The square root of 1221222121 is about 34945.9886253058. The cubic root of 1221222121 is about 1068.8864068749.

Adding to 1221222121 its reverse (1212221221), we get a palindrome (2433443342).

It can be divided in two parts, 1 and 221222121, that added together give a palindrome (221222122).

The spelling of 1221222121 in words is "one billion, two hundred twenty-one million, two hundred twenty-two thousand, one hundred twenty-one".