21202020221 has 8 divisors (see below), whose sum is σ = 21523292544. Its totient is φ = 20880889920.

The previous prime is 21202020199. The next prime is 21202020233. The reversal of 21202020221 is 12202020212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21202020221 - 2⁶ = 21202020157 is a prime.

It is a super-2 number, since 2×21202020221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202020196 and 21202020205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202020251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 287381 + ... + 353541.

It is an arithmetic number, because the mean of its divisors is an integer number (2690411568).

Almost surely, 2^21202020221 is an apocalyptic number.

It is an amenable number.

21202020221 is a deficient number, since it is larger than the sum of its proper divisors (321272323).

21202020221 is an equidigital number, since it uses as much as digits as its factorization.

21202020221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71011.

The product of its (nonzero) digits is 64, while the sum is 14.

Adding to 21202020221 its reverse (12202020212), we get a palindrome (33404040433).

Subtracting from 21202020221 its reverse (12202020212), we obtain a palindrome (9000000009).

The spelling of 21202020221 in words is "twenty-one billion, two hundred two million, twenty thousand, two hundred twenty-one".