21636166 has 8 divisors (see below), whose sum is σ = 32477760. Its totient is φ = 10810248.

The previous prime is 21636163. The next prime is 21636187. The reversal of 21636166 is 66163612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636161) 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, 555 + ... + 6601.

It is an arithmetic number, because the mean of its divisors is an integer number (4059720).

Almost surely, 2^21636166 is an apocalyptic number.

21636166 is a deficient number, since it is larger than the sum of its proper divisors (10841594).

21636166 is a wasteful number, since it uses less digits than its factorization.

21636166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7838.

The product of its digits is 7776, while the sum is 31.

The square root of 21636166 is about 4651.4692302540. The cubic root of 21636166 is about 278.6506764047.

Adding to 21636166 its reverse (66163612), we get a palindrome (87799778).

The spelling of 21636166 in words is "twenty-one million, six hundred thirty-six thousand, one hundred sixty-six".