21118693 has 4 divisors (see below), whose sum is σ = 21156768. Its totient is φ = 21080620.

The previous prime is 21118663. The next prime is 21118717. The reversal of 21118693 is 39681112.

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 21118693 - 2⁵ = 21118661 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21118613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18193 + ... + 19318.

It is an arithmetic number, because the mean of its divisors is an integer number (5289192).

Almost surely, 2^21118693 is an apocalyptic number.

It is an amenable number.

21118693 is a deficient number, since it is larger than the sum of its proper divisors (38075).

21118693 is an equidigital number, since it uses as much as digits as its factorization.

21118693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38074.

The product of its digits is 2592, while the sum is 31.

The square root of 21118693 is about 4595.5079153452. The cubic root of 21118693 is about 276.4112271111.

The spelling of 21118693 in words is "twenty-one million, one hundred eighteen thousand, six hundred ninety-three".