21606173 has 4 divisors (see below), whose sum is σ = 22743360. Its totient is φ = 20468988.

The previous prime is 21606161. The next prime is 21606191. The reversal of 21606173 is 37160612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21606173 - 2¹⁶ = 21540637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 568565 + ... + 568602.

It is an arithmetic number, because the mean of its divisors is an integer number (5685840).

Almost surely, 2^21606173 is an apocalyptic number.

It is an amenable number.

21606173 is a deficient number, since it is larger than the sum of its proper divisors (1137187).

21606173 is a wasteful number, since it uses less digits than its factorization.

21606173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1137186.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21606173 is about 4648.2440770682. The cubic root of 21606173 is about 278.5218576082.

Adding to 21606173 its reverse (37160612), we get a palindrome (58766785).

The spelling of 21606173 in words is "twenty-one million, six hundred six thousand, one hundred seventy-three".