21135237 has 16 divisors (see below), whose sum is σ = 28625088. Its totient is φ = 13870080.

The previous prime is 21135227. The next prime is 21135259. The reversal of 21135237 is 73253112.

It is not a de Polignac number, because 21135237 - 2⁶ = 21135173 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135227) 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, 100062 + ... + 100272.

It is an arithmetic number, because the mean of its divisors is an integer number (1789068).

Almost surely, 2^21135237 is an apocalyptic number.

It is an amenable number.

21135237 is a deficient number, since it is larger than the sum of its proper divisors (7489851).

21135237 is a wasteful number, since it uses less digits than its factorization.

21135237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580.

The product of its digits is 1260, while the sum is 24.

The square root of 21135237 is about 4597.3075816177. The cubic root of 21135237 is about 276.4833867809.

Adding to 21135237 its reverse (73253112), we get a palindrome (94388349).

The spelling of 21135237 in words is "twenty-one million, one hundred thirty-five thousand, two hundred thirty-seven".