21032220 has 72 divisors (see below), whose sum is σ = 64752912. Its totient is φ = 5096960.

The previous prime is 21032201. The next prime is 21032237. The reversal of 21032220 is 2223012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21032196 and 21032205.

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, 5812 + ... + 8708.

It is an arithmetic number, because the mean of its divisors is an integer number (899346).

Almost surely, 2^21032220 is an apocalyptic number.

21032220 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 21032220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32376456).

21032220 is an abundant number, since it is smaller than the sum of its proper divisors (43720692).

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

21032220 is a wasteful number, since it uses less digits than its factorization.

21032220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2931 (or 2918 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21032220 is about 4586.0898377594. The cubic root of 21032220 is about 276.0334448024.

Adding to 21032220 its reverse (2223012), we get a palindrome (23255232).

The spelling of 21032220 in words is "twenty-one million, thirty-two thousand, two hundred twenty".