1221321311220 has 48 divisors (see below), whose sum is σ = 3419747795520. Its totient is φ = 325681099776.

The previous prime is 1221321311191. The next prime is 1221321311227. The reversal of 1221321311220 is 221131231221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221321311227) 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, 7760676 + ... + 7916484.

It is an arithmetic number, because the mean of its divisors is an integer number (71244745740).

Almost surely, 2^{1221321311220} is an apocalyptic number.

1221321311220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221321311220 is an abundant number, since it is smaller than the sum of its proper divisors (2198426484300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221321311220 is a wasteful number, since it uses less digits than its factorization.

1221321311220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286464 (or 286462 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

Adding to 1221321311220 its reverse (221131231221), we get a palindrome (1442452542441).

The spelling of 1221321311220 in words is "one trillion, two hundred twenty-one billion, three hundred twenty-one million, three hundred eleven thousand, two hundred twenty".