221021111021 has 4 divisors (see below), whose sum is σ = 221022194844. Its totient is φ = 221020027200.

The previous prime is 221021110993. The next prime is 221021111053. The reversal of 221021111021 is 120111120122.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 43716955396 + 177304155625 = 209086^2 + 421075^2 .

It is a cyclic number.

It is not a de Polignac number, because 221021111021 - 2¹⁸ = 221020848877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221021110987 and 221021111005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221021111071) 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, 133340 + ... + 678101.

It is an arithmetic number, because the mean of its divisors is an integer number (55255548711).

Almost surely, 2^221021111021 is an apocalyptic number.

It is an amenable number.

221021111021 is a deficient number, since it is larger than the sum of its proper divisors (1083823).

221021111021 is an equidigital number, since it uses as much as digits as its factorization.

221021111021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083822.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 221021111021 its reverse (120111120122), we get a palindrome (341132231143).

The spelling of 221021111021 in words is "two hundred twenty-one billion, twenty-one million, one hundred eleven thousand, twenty-one".