21116806 has 16 divisors (see below), whose sum is σ = 33156864. Its totient is φ = 10067464.

The previous prime is 21116801. The next prime is 21116819. The reversal of 21116806 is 60861112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20991 + ... + 21973.

It is an arithmetic number, because the mean of its divisors is an integer number (2072304).

Almost surely, 2^21116806 is an apocalyptic number.

21116806 is a deficient number, since it is larger than the sum of its proper divisors (12040058).

21116806 is a wasteful number, since it uses less digits than its factorization.

21116806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1475.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21116806 is about 4595.3026015704. The cubic root of 21116806 is about 276.4029942228.

Adding to 21116806 its reverse (60861112), we get a palindrome (81977918).

The spelling of 21116806 in words is "twenty-one million, one hundred sixteen thousand, eight hundred six".