21606163 has 6 divisors (see below), whose sum is σ = 22326612. Its totient is φ = 20908260.

The previous prime is 21606161. The next prime is 21606191. The reversal of 21606163 is 36160612.

It is not a de Polignac number, because 21606163 - 2¹ = 21606161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21606161) 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 in 5 ways as a sum of consecutive naturals, for example, 10281 + ... + 12202.

It is an arithmetic number, because the mean of its divisors is an integer number (3721102).

Almost surely, 2^21606163 is an apocalyptic number.

21606163 is a deficient number, since it is larger than the sum of its proper divisors (720449).

21606163 is an equidigital number, since it uses as much as digits as its factorization.

21606163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22545 (or 22514 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21606163 is about 4648.2430013931. The cubic root of 21606163 is about 278.5218146388.

Adding to 21606163 its reverse (36160612), we get a palindrome (57766775).

The spelling of 21606163 in words is "twenty-one million, six hundred six thousand, one hundred sixty-three".