21130221 has 12 divisors (see below), whose sum is σ = 32773632. Its totient is φ = 12074328.

The previous prime is 21130111. The next prime is 21130231. The reversal of 21130221 is 12203112.

It is not a de Polignac number, because 21130221 - 2¹⁴ = 21113837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21130197 and 21130206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 71725 + ... + 72018.

It is an arithmetic number, because the mean of its divisors is an integer number (2731136).

Almost surely, 2^21130221 is an apocalyptic number.

21130221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21130221 is a deficient number, since it is larger than the sum of its proper divisors (11643411).

21130221 is a wasteful number, since it uses less digits than its factorization.

21130221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143760 (or 143753 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21130221 is about 4596.7620125475. The cubic root of 21130221 is about 276.4615125621.

Adding to 21130221 its reverse (12203112), we get a palindrome (33333333).

The spelling of 21130221 in words is "twenty-one million, one hundred thirty thousand, two hundred twenty-one".