21021300 has 54 divisors (see below), whose sum is σ = 65892918. Its totient is φ = 5605440.

The previous prime is 21021293. The next prime is 21021323. The reversal of 21021300 is 312012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 3481956 + 17539344 = 1866^2 + 4188^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 10779 + ... + 12578.

Almost surely, 2^21021300 is an apocalyptic number.

21021300 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021300 is an abundant number, since it is smaller than the sum of its proper divisors (44871618).

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

21021300 is a wasteful number, since it uses less digits than its factorization.

21021300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23377 (or 23367 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21021300 is about 4584.8991264803. The cubic root of 21021300 is about 275.9856640317.

Adding to 21021300 its reverse (312012), we get a palindrome (21333312).

It can be divided in two parts, 21021 and 300, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21021300 in words is "twenty-one million, twenty-one thousand, three hundred".