21020213221 has 4 divisors (see below), whose sum is σ = 24023100832. Its totient is φ = 18017325612.

The previous prime is 21020213189. The next prime is 21020213251. The reversal of 21020213221 is 12231202012.

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 21020213221 - 2⁵ = 21020213189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020213195 and 21020213204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020213251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1501443795 + ... + 1501443808.

It is an arithmetic number, because the mean of its divisors is an integer number (6005775208).

Almost surely, 2^21020213221 is an apocalyptic number.

It is an amenable number.

21020213221 is a deficient number, since it is larger than the sum of its proper divisors (3002887611).

21020213221 is an equidigital number, since it uses as much as digits as its factorization.

21020213221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3002887610.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21020213221 its reverse (12231202012), we get a palindrome (33251415233).

The spelling of 21020213221 in words is "twenty-one billion, twenty million, two hundred thirteen thousand, two hundred twenty-one".