21116685 has 16 divisors (see below), whose sum is σ = 33892416. Its totient is φ = 11227008.

The previous prime is 21116663. The next prime is 21116687. The reversal of 21116685 is 58661112.

It is not a de Polignac number, because 21116685 - 2⁵ = 21116653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116687) 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 15 ways as a sum of consecutive naturals, for example, 3177 + ... + 7233.

It is an arithmetic number, because the mean of its divisors is an integer number (2118276).

Almost surely, 2^21116685 is an apocalyptic number.

It is an amenable number.

21116685 is a deficient number, since it is larger than the sum of its proper divisors (12775731).

21116685 is a wasteful number, since it uses less digits than its factorization.

21116685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4412.

The product of its digits is 2880, while the sum is 30.

The square root of 21116685 is about 4595.2894359333. The cubic root of 21116685 is about 276.4024662890.

Adding to 21116685 its reverse (58661112), we get a palindrome (79777797).

The spelling of 21116685 in words is "twenty-one million, one hundred sixteen thousand, six hundred eighty-five".