21006328 has 16 divisors (see below), whose sum is σ = 45013680. Its totient is φ = 9002688.

The previous prime is 21006311. The next prime is 21006329. The reversal of 21006328 is 82360012.

It is a junction number, because it is equal to n+sod(n) for n = 21006299 and 21006308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006329) 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 3 ways as a sum of consecutive naturals, for example, 187501 + ... + 187612.

It is an arithmetic number, because the mean of its divisors is an integer number (2813355).

Almost surely, 2^21006328 is an apocalyptic number.

21006328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21006328 is an abundant number, since it is smaller than the sum of its proper divisors (24007352).

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

21006328 is a wasteful number, since it uses less digits than its factorization.

21006328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375126 (or 375122 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21006328 is about 4583.2660843551. The cubic root of 21006328 is about 275.9201267157.

The spelling of 21006328 in words is "twenty-one million, six thousand, three hundred twenty-eight".