21130332221 has 4 divisors (see below), whose sum is σ = 21167468700. Its totient is φ = 21093195744.

The previous prime is 21130332211. The next prime is 21130332233. The reversal of 21130332221 is 12223303112.

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 6151264900 + 14979067321 = 78430^2 + 122389^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21130332221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21130332193 and 21130332202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130332211) 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, 18567386 + ... + 18568523.

It is an arithmetic number, because the mean of its divisors is an integer number (5291867175).

Almost surely, 2^21130332221 is an apocalyptic number.

It is an amenable number.

21130332221 is a deficient number, since it is larger than the sum of its proper divisors (37136479).

21130332221 is an equidigital number, since it uses as much as digits as its factorization.

21130332221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37136478.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21130332221 its reverse (12223303112), we get a palindrome (33353635333).

The spelling of 21130332221 in words is "twenty-one billion, one hundred thirty million, three hundred thirty-two thousand, two hundred twenty-one".