1221000122221 has 12 divisors (see below), whose sum is σ = 1355379087132. Its totient is φ = 1099010000000.

The previous prime is 1221000122219. The next prime is 1221000122263. The reversal of 1221000122221 is 1222210001221.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 964351496196 + 256648626025 = 982014^2 + 506605^2 .

It is not a de Polignac number, because 1221000122221 - 2¹ = 1221000122219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221000122195 and 1221000122204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221000122201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49942780 + ... + 49967221.

It is an arithmetic number, because the mean of its divisors is an integer number (112948257261).

Almost surely, 2^{1221000122221} is an apocalyptic number.

1221000122221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221000122221 is a deficient number, since it is larger than the sum of its proper divisors (134378964911).

1221000122221 is a wasteful number, since it uses less digits than its factorization.

1221000122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99910124 (or 99910113 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 1221000122221 its reverse (1222210001221), we get a palindrome (2443210123442).

The spelling of 1221000122221 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-two thousand, two hundred twenty-one".