21165238 has 16 divisors (see below), whose sum is σ = 33708960. Its totient is φ = 9932416.

The previous prime is 21165229. The next prime is 21165241. The reversal of 21165238 is 83256112.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 16695 + ... + 17917.

It is an arithmetic number, because the mean of its divisors is an integer number (2106810).

Almost surely, 2^21165238 is an apocalyptic number.

21165238 is a deficient number, since it is larger than the sum of its proper divisors (12543722).

21165238 is a wasteful number, since it uses less digits than its factorization.

21165238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751.

The product of its digits is 2880, while the sum is 28.

The square root of 21165238 is about 4600.5693125960. The cubic root of 21165238 is about 276.6141456084.

The spelling of 21165238 in words is "twenty-one million, one hundred sixty-five thousand, two hundred thirty-eight".