21003135 has 16 divisors (see below), whose sum is σ = 34387584. Its totient is φ = 10940832.

The previous prime is 21003121. The next prime is 21003139. The reversal of 21003135 is 53130012.

It is a happy number.

It is not a de Polignac number, because 21003135 - 2⁹ = 21002623 is a prime.

It is a super-2 number, since 2×21003135² = 882263359656450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003139) 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, 15637 + ... + 16926.

It is an arithmetic number, because the mean of its divisors is an integer number (2149224).

Almost surely, 2^21003135 is an apocalyptic number.

21003135 is a deficient number, since it is larger than the sum of its proper divisors (13384449).

21003135 is a wasteful number, since it uses less digits than its factorization.

21003135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32614.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21003135 is about 4582.9177387337. The cubic root of 21003135 is about 275.9061458872.

Adding to 21003135 its reverse (53130012), we get a palindrome (74133147).

The spelling of 21003135 in words is "twenty-one million, three thousand, one hundred thirty-five".