21020200221 has 4 divisors (see below), whose sum is σ = 28026933632. Its totient is φ = 14013466812.

The previous prime is 21020200219. The next prime is 21020200231. The reversal of 21020200221 is 12200202012.

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 not a de Polignac number, because 21020200221 - 2¹ = 21020200219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020200197 and 21020200206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020200231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3503366701 + ... + 3503366706.

It is an arithmetic number, because the mean of its divisors is an integer number (7006733408).

Almost surely, 2^21020200221 is an apocalyptic number.

It is an amenable number.

21020200221 is a deficient number, since it is larger than the sum of its proper divisors (7006733411).

21020200221 is an equidigital number, since it uses as much as digits as its factorization.

21020200221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7006733410.

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21020200221 its reverse (12200202012), we get a palindrome (33220402233).

The spelling of 21020200221 in words is "twenty-one billion, twenty million, two hundred thousand, two hundred twenty-one".