21214247 has 2 divisors, whose sum is σ = 21214248. Its totient is φ = 21214246.

The previous prime is 21214231. The next prime is 21214253. The reversal of 21214247 is 74241212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21214247 - 2⁴ = 21214231 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21214267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607123 + 10607124.

It is an arithmetic number, because the mean of its divisors is an integer number (10607124).

Almost surely, 2^21214247 is an apocalyptic number.

21214247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21214247 is an equidigital number, since it uses as much as digits as its factorization.

21214247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 896, while the sum is 23.

The square root of 21214247 is about 4605.8926387835. The cubic root of 21214247 is about 276.8274849291.

Adding to 21214247 its reverse (74241212), we get a palindrome (95455459).

The spelling of 21214247 in words is "twenty-one million, two hundred fourteen thousand, two hundred forty-seven".