21087118 has 16 divisors (see below), whose sum is σ = 35239680. Its totient is φ = 9396576.

The previous prime is 21087061. The next prime is 21087133. The reversal of 21087118 is 81178012.

It is a congruent number.

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, 13230 + ... + 14737.

It is an arithmetic number, because the mean of its divisors is an integer number (2202480).

Almost surely, 2^21087118 is an apocalyptic number.

21087118 is a deficient number, since it is larger than the sum of its proper divisors (14152562).

21087118 is a wasteful number, since it uses less digits than its factorization.

21087118 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28011.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21087118 is about 4592.0712102492. The cubic root of 21087118 is about 276.2734023294.

The spelling of 21087118 in words is "twenty-one million, eighty-seven thousand, one hundred eighteen".