21442543 has 2 divisors, whose sum is σ = 21442544. Its totient is φ = 21442542.

The previous prime is 21442501. The next prime is 21442591. The reversal of 21442543 is 34524412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21442543 - 2¹⁷ = 21311471 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21442243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721271 + 10721272.

It is an arithmetic number, because the mean of its divisors is an integer number (10721272).

Almost surely, 2^21442543 is an apocalyptic number.

21442543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21442543 is an equidigital number, since it uses as much as digits as its factorization.

21442543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3840, while the sum is 25.

The square root of 21442543 is about 4630.6093551497. The cubic root of 21442543 is about 277.8169654165.

Adding to 21442543 its reverse (34524412), we get a palindrome (55966955).

The spelling of 21442543 in words is "twenty-one million, four hundred forty-two thousand, five hundred forty-three".