21033220 has 24 divisors (see below), whose sum is σ = 47568024. Its totient is φ = 7766016.

The previous prime is 21033203. The next prime is 21033223. The reversal of 21033220 is 2233012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2663424 + 18369796 = 1632^2 + 4286^2 .

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a self number, because there is not a number n which added to its sum of digits gives 21033220.

It is not an unprimeable number, because it can be changed into a prime (21033223) 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, 40189 + ... + 40708.

It is an arithmetic number, because the mean of its divisors is an integer number (1982001).

Almost surely, 2^21033220 is an apocalyptic number.

21033220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21033220 is an abundant number, since it is smaller than the sum of its proper divisors (26534804).

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

21033220 is a wasteful number, since it uses less digits than its factorization.

21033220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80919 (or 80917 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21033220 is about 4586.1988618027. The cubic root of 21033220 is about 276.0378195042.

Adding to 21033220 its reverse (2233012), we get a palindrome (23266232).

The spelling of 21033220 in words is "twenty-one million, thirty-three thousand, two hundred twenty".