21263328 has 144 divisors (see below), whose sum is σ = 66162096. Its totient is φ = 6451200.

The previous prime is 21263309. The next prime is 21263353. The reversal of 21263328 is 82336212.

21263328 is a `hidden beast` number, since 2 + 1 + 2 + 633 + 28 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

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, 210478 + ... + 210578.

It is an arithmetic number, because the mean of its divisors is an integer number (459459).

Almost surely, 2^21263328 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 21263328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33081048).

21263328 is an abundant number, since it is smaller than the sum of its proper divisors (44898768).

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

21263328 is a wasteful number, since it uses less digits than its factorization.

21263328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 166 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21263328 is about 4611.2176266145. The cubic root of 21263328 is about 277.0408086296.

The spelling of 21263328 in words is "twenty-one million, two hundred sixty-three thousand, three hundred twenty-eight".