221221111211021 has 4 divisors (see below), whose sum is σ = 221221423556544. Its totient is φ = 221220798865500.

The previous prime is 221221111210999. The next prime is 221221111211027. The reversal of 221221111211021 is 120112111122122.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221221111211021 - 2¹⁰ = 221221111209997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221221111210984 and 221221111211002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221221111211027) 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, 155107955 + ... + 156527696.

It is an arithmetic number, because the mean of its divisors is an integer number (55305355889136).

Almost surely, 2^{221221111211021} is an apocalyptic number.

It is an amenable number.

221221111211021 is a deficient number, since it is larger than the sum of its proper divisors (312345523).

221221111211021 is an equidigital number, since it uses as much as digits as its factorization.

221221111211021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312345522.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 221221111211021 its reverse (120112111122122), we get a palindrome (341333222333143).

The spelling of 221221111211021 in words is "two hundred twenty-one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred eleven thousand, twenty-one".