21006135 has 64 divisors (see below), whose sum is σ = 40383360. Its totient is φ = 10450944.

The previous prime is 21006119. The next prime is 21006137. The reversal of 21006135 is 53160012.

It is not a de Polignac number, because 21006135 - 2⁴ = 21006119 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 185839 + ... + 185951.

It is an arithmetic number, because the mean of its divisors is an integer number (630990).

Almost surely, 2^21006135 is an apocalyptic number.

21006135 is a deficient number, since it is larger than the sum of its proper divisors (19377225).

21006135 is an equidigital number, since it uses as much as digits as its factorization.

21006135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21006135 is about 4583.2450294524. The cubic root of 21006135 is about 275.9192816886.

Adding to 21006135 its reverse (53160012), we get a palindrome (74166147).

The spelling of 21006135 in words is "twenty-one million, six thousand, one hundred thirty-five".