1221302121 has 16 divisors (see below), whose sum is σ = 1845963840. Its totient is φ = 712013760.

The previous prime is 1221302119. The next prime is 1221302149. The reversal of 1221302121 is 1212031221.

It is not a de Polignac number, because 1221302121 - 2¹ = 1221302119 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221302121.

It is not an unprimeable number, because it can be changed into a prime (1221302101) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 823350 + ... + 824831.

It is an arithmetic number, because the mean of its divisors is an integer number (115372740).

Almost surely, 2^1221302121 is an apocalyptic number.

It is an amenable number.

1221302121 is a deficient number, since it is larger than the sum of its proper divisors (624661719).

1221302121 is a wasteful number, since it uses less digits than its factorization.

1221302121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1648216.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 1221302121 is about 34947.1332300662. The cubic root of 1221302121 is about 1068.9097466217.

Adding to 1221302121 its reverse (1212031221), we get a palindrome (2433333342).

It can be divided in two parts, 122130 and 2121, that added together give a triangular number (124251 = T₄₉₈).

The spelling of 1221302121 in words is "one billion, two hundred twenty-one million, three hundred two thousand, one hundred twenty-one".