21273538 has 16 divisors (see below), whose sum is σ = 37489536. Its totient is φ = 8925840.

The previous prime is 21273509. The next prime is 21273583. The reversal of 21273538 is 83537212.

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, 36906 + ... + 37477.

It is an arithmetic number, because the mean of its divisors is an integer number (2343096).

Almost surely, 2^21273538 is an apocalyptic number.

21273538 is a deficient number, since it is larger than the sum of its proper divisors (16215998).

21273538 is a wasteful number, since it uses less digits than its factorization.

21273538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74409.

The product of its digits is 10080, while the sum is 31.

The square root of 21273538 is about 4612.3245766099. The cubic root of 21273538 is about 277.0851437096.

It can be divided in two parts, 2127 and 3538, that added together give a palindrome (5665).

The spelling of 21273538 in words is "twenty-one million, two hundred seventy-three thousand, five hundred thirty-eight".