1221320404206 has 384 divisors, whose sum is σ = 3447019929600. Its totient is φ = 304147768320.

The previous prime is 1221320404193. The next prime is 1221320404207. The reversal of 1221320404206 is 6024040231221.

1221320404206 is a `hidden beast` number, since 1 + 2 + 21 + 32 + 0 + 404 + 206 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1221320404206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221320404207) 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 191 ways as a sum of consecutive naturals, for example, 458624431 + ... + 458627093.

It is an arithmetic number, because the mean of its divisors is an integer number (8976614400).

Almost surely, 2^{1221320404206} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221320404206, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1723509964800).

1221320404206 is an abundant number, since it is smaller than the sum of its proper divisors (2225699525394).

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

1221320404206 is a wasteful number, since it uses less digits than its factorization.

1221320404206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2964 (or 2961 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

Adding to 1221320404206 its reverse (6024040231221), we get a palindrome (7245360635427).

The spelling of 1221320404206 in words is "one trillion, two hundred twenty-one billion, three hundred twenty million, four hundred four thousand, two hundred six".