21210202221 has 16 divisors (see below), whose sum is σ = 30476322240. Its totient is φ = 13043583360.

The previous prime is 21210202219. The next prime is 21210202229. The reversal of 21210202221 is 12220201212.

It is not a de Polignac number, because 21210202221 - 2¹ = 21210202219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21210202221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210202229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125851 + ... + 241368.

It is an arithmetic number, because the mean of its divisors is an integer number (1904770140).

Almost surely, 2^21210202221 is an apocalyptic number.

It is an amenable number.

21210202221 is a deficient number, since it is larger than the sum of its proper divisors (9266120019).

21210202221 is a wasteful number, since it uses less digits than its factorization.

21210202221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368716.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21210202221 its reverse (12220201212), we get a palindrome (33430403433).

The spelling of 21210202221 in words is "twenty-one billion, two hundred ten million, two hundred two thousand, two hundred twenty-one".