21165242 has 32 divisors (see below), whose sum is σ = 37324800. Its totient is φ = 8814960.

The previous prime is 21165241. The next prime is 21165251. The reversal of 21165242 is 24256112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21165241) 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 in 15 ways as a sum of consecutive naturals, for example, 106259 + ... + 106457.

It is an arithmetic number, because the mean of its divisors is an integer number (1166400).

Almost surely, 2^21165242 is an apocalyptic number.

21165242 is a deficient number, since it is larger than the sum of its proper divisors (16159558).

21165242 is a wasteful number, since it uses less digits than its factorization.

21165242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386.

The product of its digits is 960, while the sum is 23.

The square root of 21165242 is about 4600.5697473248. The cubic root of 21165242 is about 276.6141630341.

The spelling of 21165242 in words is "twenty-one million, one hundred sixty-five thousand, two hundred forty-two".