1221221432021 has 4 divisors (see below), whose sum is σ = 1225123098252. Its totient is φ = 1217319765792.

The previous prime is 1221221432003. The next prime is 1221221432071. The reversal of 1221221432021 is 1202341221221.

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 151506999121 + 1069714432900 = 389239^2 + 1034270^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221221432021 - 2¹⁸ = 1221221169877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221221432071) 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, 1950832646 + ... + 1950833271.

It is an arithmetic number, because the mean of its divisors is an integer number (306280774563).

Almost surely, 2^{1221221432021} is an apocalyptic number.

It is an amenable number.

1221221432021 is a deficient number, since it is larger than the sum of its proper divisors (3901666231).

1221221432021 is an equidigital number, since it uses as much as digits as its factorization.

1221221432021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3901666230.

The product of its (nonzero) digits is 768, while the sum is 23.

Adding to 1221221432021 its reverse (1202341221221), we get a palindrome (2423562653242).

The spelling of 1221221432021 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, four hundred thirty-two thousand, twenty-one".