21636143 has 2 divisors, whose sum is σ = 21636144. Its totient is φ = 21636142.

The previous prime is 21636107. The next prime is 21636161. The reversal of 21636143 is 34163612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21636143 - 2¹⁶ = 21570607 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21636163) 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, 10818071 + 10818072.

It is an arithmetic number, because the mean of its divisors is an integer number (10818072).

Almost surely, 2^21636143 is an apocalyptic number.

21636143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21636143 is an equidigital number, since it uses as much as digits as its factorization.

21636143 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 26.

The square root of 21636143 is about 4651.4667579163. The cubic root of 21636143 is about 278.6505776662.

Adding to 21636143 its reverse (34163612), we get a palindrome (55799755).

The spelling of 21636143 in words is "twenty-one million, six hundred thirty-six thousand, one hundred forty-three".