1221021121 has 4 divisors (see below), whose sum is σ = 1221545044. Its totient is φ = 1220497200.

The previous prime is 1221021119. The next prime is 1221021173. The reversal of 1221021121 is 1211201221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1211201221 = 1447 ⋅837043.

It can be written as a sum of positive squares in 2 ways, for example, as 820020496 + 401000625 = 28636^2 + 20025^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221021121 - 2¹ = 1221021119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221021721) 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, 258450 + ... + 263131.

It is an arithmetic number, because the mean of its divisors is an integer number (305386261).

Almost surely, 2^1221021121 is an apocalyptic number.

It is an amenable number.

1221021121 is a deficient number, since it is larger than the sum of its proper divisors (523923).

1221021121 is an equidigital number, since it uses as much as digits as its factorization.

1221021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523922.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1221021121 is about 34943.1126404045. The cubic root of 1221021121 is about 1068.8277612629.

Adding to 1221021121 its reverse (1211201221), we get a palindrome (2432222342).

The spelling of 1221021121 in words is "one billion, two hundred twenty-one million, twenty-one thousand, one hundred twenty-one".