21033520 has 40 divisors (see below), whose sum is σ = 49233456. Its totient is φ = 8356608.

The previous prime is 21033517. The next prime is 21033521. The reversal of 21033520 is 2533012.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 21033494 and 21033503.

It is not an unprimeable number, because it can be changed into a prime (21033521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12234 + ... + 13846.

Almost surely, 2^21033520 is an apocalyptic number.

21033520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21033520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24616728).

21033520 is an abundant number, since it is smaller than the sum of its proper divisors (28199936).

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

21033520 is a wasteful number, since it uses less digits than its factorization.

21033520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1789 (or 1783 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 16.

The square root of 21033520 is about 4586.2315685103. The cubic root of 21033520 is about 276.0391318876.

Adding to 21033520 its reverse (2533012), we get a palindrome (23566532).

The spelling of 21033520 in words is "twenty-one million, thirty-three thousand, five hundred twenty".