21135 has 8 divisors (see below), whose sum is σ = 33840. Its totient is φ = 11264.

The previous prime is 21121. The next prime is 21139. The reversal of 21135 is 53112.

21135 = 63² + 64² + ... + 67².

21135 is digitally balanced in base 4 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21135 - 2⁸ = 20879 is a prime.

21135 is strictly pandigital in base 6.

It is a self number, because there is not a number n which added to its sum of digits gives 21135.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21139) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 690 + ... + 719.

It is an arithmetic number, because the mean of its divisors is an integer number (4230).

2²¹¹³⁵ is an apocalyptic number.

21135 is a deficient number, since it is larger than the sum of its proper divisors (12705).

21135 is a wasteful number, since it uses less digits than its factorization.

21135 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1417.

The product of its digits is 30, while the sum is 12.

The square root of 21135 is about 145.3788155131. The cubic root of 21135 is about 27.6482353328.

Adding to 21135 its reverse (53112), we get a palindrome (74247).

The spelling of 21135 in words is "twenty-one thousand, one hundred thirty-five".