221121011221021 has 4 divisors (see below), whose sum is σ = 221121062761500. Its totient is φ = 221120959680544.

The previous prime is 221121011221003. The next prime is 221121011221039. The reversal of 221121011221021 is 120122110121122.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (221121011221003) and next prime (221121011221039).

It can be written as a sum of positive squares in 2 ways, for example, as 59966593316100 + 161154417904921 = 7743810^2 + 12694661^2 .

It is a cyclic number.

It is not a de Polignac number, because 221121011221021 - 2²⁷ = 221120877003293 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 221121011221021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221121011521021) 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, 18685666 + ... + 28131763.

It is an arithmetic number, because the mean of its divisors is an integer number (55280265690375).

Almost surely, 2^{221121011221021} is an apocalyptic number.

It is an amenable number.

221121011221021 is a deficient number, since it is larger than the sum of its proper divisors (51540479).

221121011221021 is an equidigital number, since it uses as much as digits as its factorization.

221121011221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51540478.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 221121011221021 its reverse (120122110121122), we get a palindrome (341243121342143).

The spelling of 221121011221021 in words is "two hundred twenty-one trillion, one hundred twenty-one billion, eleven million, two hundred twenty-one thousand, twenty-one".