21068518 has 4 divisors (see below), whose sum is σ = 31602780. Its totient is φ = 10534258.

The previous prime is 21068513. The next prime is 21068519. The reversal of 21068518 is 81586012.

It is a semiprime because it is the product of two primes.

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 self number, because there is not a number n which added to its sum of digits gives 21068518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21068513) 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 as a sum of consecutive naturals, namely, 5267128 + ... + 5267131.

It is an arithmetic number, because the mean of its divisors is an integer number (7900695).

Almost surely, 2^21068518 is an apocalyptic number.

21068518 is a deficient number, since it is larger than the sum of its proper divisors (10534262).

21068518 is a wasteful number, since it uses less digits than its factorization.

21068518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10534261.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 21068518 is about 4590.0455335432. The cubic root of 21068518 is about 276.1921489801.

The spelling of 21068518 in words is "twenty-one million, sixty-eight thousand, five hundred eighteen".