21026016 has 72 divisors (see below), whose sum is σ = 65238264. Its totient is φ = 6370560.

The previous prime is 21025987. The next prime is 21026053. The reversal of 21026016 is 61062012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a self number, because there is not a number n which added to its sum of digits gives 21026016.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 151 + ... + 6486.

It is an arithmetic number, because the mean of its divisors is an integer number (906087).

Almost surely, 2^21026016 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 21026016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32619132).

21026016 is an abundant number, since it is smaller than the sum of its proper divisors (44212248).

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

21026016 is a wasteful number, since it uses less digits than its factorization.

21026016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6664 (or 6653 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 21026016 is about 4585.4133946679. The cubic root of 21026016 is about 276.0063010534.

Adding to 21026016 its reverse (61062012), we get a palindrome (82088028).

It can be divided in two parts, 210260 and 16, that added together give a triangular number (210276 = T₆₄₈).

The spelling of 21026016 in words is "twenty-one million, twenty-six thousand, sixteen".