21328776 has 96 divisors (see below), whose sum is σ = 66830400. Its totient is φ = 6019200.

The previous prime is 21328763. The next prime is 21328781. The reversal of 21328776 is 67782312.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21328776.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 50695 + ... + 51113.

It is an arithmetic number, because the mean of its divisors is an integer number (696150).

Almost surely, 2^21328776 is an apocalyptic number.

21328776 is the 3771-st pentagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21328776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33415200).

21328776 is an abundant number, since it is smaller than the sum of its proper divisors (45501624).

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

21328776 is a wasteful number, since it uses less digits than its factorization.

21328776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 539 (or 532 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21328776 is about 4618.3087813614. The cubic root of 21328776 is about 277.3247590935.

The spelling of 21328776 in words is "twenty-one million, three hundred twenty-eight thousand, seven hundred seventy-six".