21003300 has 90 divisors (see below), whose sum is σ = 68110658. Its totient is φ = 5598720.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003300 is 330012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 1871424 + 19131876 = 1368^2 + 4374^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a super-2 number, since 2×21003300² = 882277221780000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

21003300 is a modest number, since divided by 3300 gives 2100 as remainder.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 6804 + ... + 9396.

Almost surely, 2^21003300 is an apocalyptic number.

21003300 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 21003300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34055329).

21003300 is an abundant number, since it is smaller than the sum of its proper divisors (47107358).

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

21003300 is a wasteful number, since it uses less digits than its factorization.

21003300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2619 (or 2603 counting only the distinct ones).

The product of its (nonzero) digits is 18, while the sum is 9.

The square root of 21003300 is about 4582.9357403306. The cubic root of 21003300 is about 275.9068683888.

Adding to 21003300 its reverse (330012), we get a palindrome (21333312).

The spelling of 21003300 in words is "twenty-one million, three thousand, three hundred".