21318047 has 2 divisors, whose sum is σ = 21318048. Its totient is φ = 21318046.

The previous prime is 21318007. The next prime is 21318091. The reversal of 21318047 is 74081312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21318047 - 2¹² = 21313951 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 (21318007) 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 as a sum of consecutive naturals, namely, 10659023 + 10659024.

It is an arithmetic number, because the mean of its divisors is an integer number (10659024).

Almost surely, 2^21318047 is an apocalyptic number.

21318047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21318047 is an equidigital number, since it uses as much as digits as its factorization.

21318047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21318047 is about 4617.1470628517. The cubic root of 21318047 is about 277.2782504645.

Adding to 21318047 its reverse (74081312), we get a palindrome (95399359).

The spelling of 21318047 in words is "twenty-one million, three hundred eighteen thousand, forty-seven".