21135168 has 112 divisors (see below), whose sum is σ = 63317120. Its totient is φ = 6998400.

The previous prime is 21135161. The next prime is 21135173. The reversal of 21135168 is 86153112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135161) 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 15 ways as a sum of consecutive naturals, for example, 139893 + ... + 140043.

Almost surely, 2^21135168 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21135168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31658560).

21135168 is an abundant number, since it is smaller than the sum of its proper divisors (42181952).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21135168 is an frugal number, since it uses more digits than its factorization.

21135168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184 (or 156 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 21135168 is about 4597.3000772192. The cubic root of 21135168 is about 276.4830859031.

The spelling of 21135168 in words is "twenty-one million, one hundred thirty-five thousand, one hundred sixty-eight".