21135648 has 24 divisors (see below), whose sum is σ = 55481328. Its totient is φ = 7045184.

The previous prime is 21135637. The next prime is 21135649. The reversal of 21135648 is 84653112.

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (21135649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109986 + ... + 110177.

It is an arithmetic number, because the mean of its divisors is an integer number (2311722).

Almost surely, 2^21135648 is an apocalyptic number.

It is an amenable number.

21135648 is an abundant number, since it is smaller than the sum of its proper divisors (34345680).

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

21135648 is a wasteful number, since it uses less digits than its factorization.

21135648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220176 (or 220168 counting only the distinct ones).

The product of its digits is 5760, while the sum is 30.

The square root of 21135648 is about 4597.3522814768. The cubic root of 21135648 is about 276.4851789528.

The spelling of 21135648 in words is "twenty-one million, one hundred thirty-five thousand, six hundred forty-eight".