21243347 has 2 divisors, whose sum is σ = 21243348. Its totient is φ = 21243346.

The previous prime is 21243331. The next prime is 21243359. The reversal of 21243347 is 74334212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21243347 - 2⁴ = 21243331 is a prime.

It is not a weakly prime, because it can be changed into another prime (21243307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621673 + 10621674.

It is an arithmetic number, because the mean of its divisors is an integer number (10621674).

Almost surely, 2^21243347 is an apocalyptic number.

21243347 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243347 is an equidigital number, since it uses as much as digits as its factorization.

21243347 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 26.

The square root of 21243347 is about 4609.0505529881. The cubic root of 21243347 is about 276.9540036665.

Adding to 21243347 its reverse (74334212), we get a palindrome (95577559).

The spelling of 21243347 in words is "twenty-one million, two hundred forty-three thousand, three hundred forty-seven".