221021200021 has 4 divisors (see below), whose sum is σ = 224644498444. Its totient is φ = 217397901600.

The previous prime is 221021199991. The next prime is 221021200069. The reversal of 221021200021 is 120002120122.

It is a happy number.

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 19227982225 + 201793217796 = 138665^2 + 449214^2 .

It is a cyclic number.

It is not a de Polignac number, because 221021200021 - 2¹³ = 221021191829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221021199974 and 221021200010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221021200121) 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, 1811649120 + ... + 1811649241.

It is an arithmetic number, because the mean of its divisors is an integer number (56161124611).

Almost surely, 2^221021200021 is an apocalyptic number.

It is an amenable number.

221021200021 is a deficient number, since it is larger than the sum of its proper divisors (3623298423).

221021200021 is an equidigital number, since it uses as much as digits as its factorization.

221021200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3623298422.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 221021200021 its reverse (120002120122), we get a palindrome (341023320143).

The spelling of 221021200021 in words is "two hundred twenty-one billion, twenty-one million, two hundred thousand, twenty-one".