1221211222021 has 16 divisors (see below), whose sum is σ = 1413415421440. Its totient is φ = 1033444863360.

The previous prime is 1221211222019. The next prime is 1221211222043. The reversal of 1221211222021 is 1202221121221.

It is not a de Polignac number, because 1221211222021 - 2¹ = 1221211222019 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221211222021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211202021) 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, 12014191 + ... + 12115411.

It is an arithmetic number, because the mean of its divisors is an integer number (88338463840).

Almost surely, 2^{1221211222021} is an apocalyptic number.

It is an amenable number.

1221211222021 is a deficient number, since it is larger than the sum of its proper divisors (192204199419).

1221211222021 is a wasteful number, since it uses less digits than its factorization.

1221211222021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123124.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 1221211222021 its reverse (1202221121221), we get a palindrome (2423432343242).

The spelling of 1221211222021 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, two hundred twenty-two thousand, twenty-one".