21242047 has 2 divisors, whose sum is σ = 21242048. Its totient is φ = 21242046.

The previous prime is 21241991. The next prime is 21242063. The reversal of 21242047 is 74024212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21242047 - 2²³ = 12853439 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 (21242077) 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, 10621023 + 10621024.

It is an arithmetic number, because the mean of its divisors is an integer number (10621024).

Almost surely, 2^21242047 is an apocalyptic number.

21242047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242047 is an equidigital number, since it uses as much as digits as its factorization.

21242047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21242047 is about 4608.9095239547. The cubic root of 21242047 is about 276.9483540930.

Adding to 21242047 its reverse (74024212), we get a palindrome (95266259).

The spelling of 21242047 in words is "twenty-one million, two hundred forty-two thousand, forty-seven".