1221204021221 has 4 divisors (see below), whose sum is σ = 1227597759744. Its totient is φ = 1214810282700.

The previous prime is 1221204021217. The next prime is 1221204021241.

It is a happy number.

1221204021221 is nontrivially palindromic in base 10.

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 1221204021221 - 2² = 1221204021217 is a prime.

It is a super-2 number, since 2×1221204021221² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221204021193 and 1221204021202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221204021241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3196868975 + ... + 3196869356.

It is an arithmetic number, because the mean of its divisors is an integer number (306899439936).

Almost surely, 2^{1221204021221} is an apocalyptic number.

It is an amenable number.

1221204021221 is a deficient number, since it is larger than the sum of its proper divisors (6393738523).

1221204021221 is an equidigital number, since it uses as much as digits as its factorization.

1221204021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6393738522.

The product of its (nonzero) digits is 256, while the sum is 20.

The spelling of 1221204021221 in words is "one trillion, two hundred twenty-one billion, two hundred four million, twenty-one thousand, two hundred twenty-one".