21242135 has 16 divisors (see below), whose sum is σ = 26360640. Its totient is φ = 16423680.

The previous prime is 21242131. The next prime is 21242153. The reversal of 21242135 is 53124212.

It is not a de Polignac number, because 21242135 - 2² = 21242131 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18251 + ... + 19379.

It is an arithmetic number, because the mean of its divisors is an integer number (1647540).

Almost surely, 2^21242135 is an apocalyptic number.

21242135 is a deficient number, since it is larger than the sum of its proper divisors (5118505).

21242135 is a wasteful number, since it uses less digits than its factorization.

21242135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1258.

The product of its digits is 480, while the sum is 20.

The square root of 21242135 is about 4608.9190706716. The cubic root of 21242135 is about 276.9487365330.

Adding to 21242135 its reverse (53124212), we get a palindrome (74366347).

The spelling of 21242135 in words is "twenty-one million, two hundred forty-two thousand, one hundred thirty-five".