21606164 has 12 divisors (see below), whose sum is σ = 37853088. Its totient is φ = 10791000.

The previous prime is 21606161. The next prime is 21606191. The reversal of 21606164 is 46160612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606161) 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, 1889 + ... + 6839.

It is an arithmetic number, because the mean of its divisors is an integer number (3154424).

Almost surely, 2^21606164 is an apocalyptic number.

It is an amenable number.

21606164 is a deficient number, since it is larger than the sum of its proper divisors (16246924).

21606164 is a wasteful number, since it uses less digits than its factorization.

21606164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6046 (or 6044 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21606164 is about 4648.2431089606. The cubic root of 21606164 is about 278.5218189357.

Adding to 21606164 its reverse (46160612), we get a palindrome (67766776).

The spelling of 21606164 in words is "twenty-one million, six hundred six thousand, one hundred sixty-four".