21533135 has 24 divisors (see below), whose sum is σ = 29646000. Its totient is φ = 14956032.

The previous prime is 21533131. The next prime is 21533143. The reversal of 21533135 is 53133512.

It is not a de Polignac number, because 21533135 - 2² = 21533131 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21533135.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533131) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13616 + ... + 15114.

It is an arithmetic number, because the mean of its divisors is an integer number (1235250).

Almost surely, 2^21533135 is an apocalyptic number.

21533135 is a deficient number, since it is larger than the sum of its proper divisors (8112865).

21533135 is a wasteful number, since it uses less digits than its factorization.

21533135 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1547 (or 1534 counting only the distinct ones).

The product of its digits is 1350, while the sum is 23.

The square root of 21533135 is about 4640.3809110891. The cubic root of 21533135 is about 278.2076627580.

Adding to 21533135 its reverse (53133512), we get a palindrome (74666647).

The spelling of 21533135 in words is "twenty-one million, five hundred thirty-three thousand, one hundred thirty-five".