1221210311221 has 4 divisors (see below), whose sum is σ = 1222719842700. Its totient is φ = 1219700779744.

The previous prime is 1221210311213. The next prime is 1221210311263. The reversal of 1221210311221 is 1221130121221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 445207883121 + 776002428100 = 667239^2 + 880910^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221210311221 - 2³ = 1221210311213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221210311621) 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, 754764526 + ... + 754766143.

It is an arithmetic number, because the mean of its divisors is an integer number (305679960675).

Almost surely, 2^{1221210311221} is an apocalyptic number.

It is an amenable number.

1221210311221 is a deficient number, since it is larger than the sum of its proper divisors (1509531479).

1221210311221 is an equidigital number, since it uses as much as digits as its factorization.

1221210311221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1509531478.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 1221210311221 its reverse (1221130121221), we get a palindrome (2442340432442).

The spelling of 1221210311221 in words is "one trillion, two hundred twenty-one billion, two hundred ten million, three hundred eleven thousand, two hundred twenty-one".