21118538 has 16 divisors (see below), whose sum is σ = 38109120. Its totient is φ = 8574336.

The previous prime is 21118529. The next prime is 21118553. The reversal of 21118538 is 83581112.

It is a self number, because there is not a number n which added to its sum of digits gives 21118538.

It is an unprimeable number.

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, 39431 + ... + 39962.

It is an arithmetic number, because the mean of its divisors is an integer number (2381820).

Almost surely, 2^21118538 is an apocalyptic number.

21118538 is a deficient number, since it is larger than the sum of its proper divisors (16990582).

21118538 is a wasteful number, since it uses less digits than its factorization.

21118538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79421.

The product of its digits is 1920, while the sum is 29.

The square root of 21118538 is about 4595.4910510195. The cubic root of 21118538 is about 276.4105508722.

The spelling of 21118538 in words is "twenty-one million, one hundred eighteen thousand, five hundred thirty-eight".