21130100221 has 4 divisors (see below), whose sum is σ = 21135266812. Its totient is φ = 21124933632.

The previous prime is 21130100191. The next prime is 21130100231. The reversal of 21130100221 is 12200103112.

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 12640504900 + 8489595321 = 112430^2 + 92139^2 .

It is a cyclic number.

It is not a de Polignac number, because 21130100221 - 2³³ = 12540165629 is a prime.

It is a super-2 number, since 2×21130100221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130100231) 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, 2577156 + ... + 2585341.

It is an arithmetic number, because the mean of its divisors is an integer number (5283816703).

Almost surely, 2^21130100221 is an apocalyptic number.

It is an amenable number.

21130100221 is a deficient number, since it is larger than the sum of its proper divisors (5166591).

21130100221 is an equidigital number, since it uses as much as digits as its factorization.

21130100221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5166590.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21130100221 its reverse (12200103112), we get a palindrome (33330203333).

The spelling of 21130100221 in words is "twenty-one billion, one hundred thirty million, one hundred thousand, two hundred twenty-one".