21130247 has 2 divisors, whose sum is σ = 21130248. Its totient is φ = 21130246.

The previous prime is 21130231. The next prime is 21130267. The reversal of 21130247 is 74203112.

It is an a-pointer prime, because the next prime (21130267) can be obtained adding 21130247 to its sum of digits (20).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21130247 - 2⁴ = 21130231 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21130267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565123 + 10565124.

It is an arithmetic number, because the mean of its divisors is an integer number (10565124).

Almost surely, 2^21130247 is an apocalyptic number.

21130247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130247 is an equidigital number, since it uses as much as digits as its factorization.

21130247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21130247 is about 4596.7648406243. The cubic root of 21130247 is about 276.4616259542.

Adding to 21130247 its reverse (74203112), we get a palindrome (95333359).

The spelling of 21130247 in words is "twenty-one million, one hundred thirty thousand, two hundred forty-seven".