21606143 has 12 divisors (see below), whose sum is σ = 23563080. Its totient is φ = 19802016.

The previous prime is 21606119. The next prime is 21606149. The reversal of 21606143 is 34160612.

It is a happy number.

It is not a de Polignac number, because 21606143 - 2⁸ = 21605887 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606149) 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 in 11 ways as a sum of consecutive naturals, for example, 28868 + ... + 29606.

It is an arithmetic number, because the mean of its divisors is an integer number (1963590).

Almost surely, 2^21606143 is an apocalyptic number.

21606143 is a deficient number, since it is larger than the sum of its proper divisors (1956937).

21606143 is a wasteful number, since it uses less digits than its factorization.

21606143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 938 (or 925 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21606143 is about 4648.2408500421. The cubic root of 21606143 is about 278.5217286997.

Adding to 21606143 its reverse (34160612), we get a palindrome (55766755).

The spelling of 21606143 in words is "twenty-one million, six hundred six thousand, one hundred forty-three".