21130211 has 4 divisors (see below), whose sum is σ = 21645624. Its totient is φ = 20614800.

The previous prime is 21130111. The next prime is 21130231. The reversal of 21130211 is 11203112.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21130211 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21130192 and 21130201.

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

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257645 + ... + 257726.

It is an arithmetic number, because the mean of its divisors is an integer number (5411406).

Almost surely, 2^21130211 is an apocalyptic number.

21130211 is a deficient number, since it is larger than the sum of its proper divisors (515413).

21130211 is an equidigital number, since it uses as much as digits as its factorization.

21130211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 515412.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21130211 is about 4596.7609248252. The cubic root of 21130211 is about 276.4614689498.

Adding to 21130211 its reverse (11203112), we get a palindrome (32333323).

The spelling of 21130211 in words is "twenty-one million, one hundred thirty thousand, two hundred eleven".