1221021200221 has 4 divisors (see below), whose sum is σ = 1221383202172. Its totient is φ = 1220659198272.

The previous prime is 1221021200213. The next prime is 1221021200291. The reversal of 1221021200221 is 1220021201221.

It is a happy number.

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 1011885105625 + 209136094596 = 1005925^2 + 457314^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221021200221 - 2³ = 1221021200213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221021200195 and 1221021200204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221021200291) 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, 180995916 + ... + 181002661.

It is an arithmetic number, because the mean of its divisors is an integer number (305345800543).

Almost surely, 2^{1221021200221} is an apocalyptic number.

It is an amenable number.

1221021200221 is a deficient number, since it is larger than the sum of its proper divisors (362001951).

1221021200221 is an equidigital number, since it uses as much as digits as its factorization.

1221021200221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362001950.

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

Adding to 1221021200221 its reverse (1220021201221), we get a palindrome (2441042401442).

The spelling of 1221021200221 in words is "one trillion, two hundred twenty-one billion, twenty-one million, two hundred thousand, two hundred twenty-one".