21130231 has 2 divisors, whose sum is σ = 21130232. Its totient is φ = 21130230.

The previous prime is 21130111. The next prime is 21130247. The reversal of 21130231 is 13203112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21130231 - 2¹¹ = 21128183 is a prime.

It is a super-2 number, since 2×21130231² = 892973324226722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21130331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565115 + 10565116.

It is an arithmetic number, because the mean of its divisors is an integer number (10565116).

Almost surely, 2^21130231 is an apocalyptic number.

21130231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130231 is an equidigital number, since it uses as much as digits as its factorization.

21130231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21130231 is about 4596.7631002696. The cubic root of 21130231 is about 276.4615561745.

Adding to 21130231 its reverse (13203112), we get a palindrome (34333343).

The spelling of 21130231 in words is "twenty-one million, one hundred thirty thousand, two hundred thirty-one".