21243300 has 108 divisors (see below), whose sum is σ = 66714480. Its totient is φ = 5216640.

The previous prime is 21243293. The next prime is 21243307. The reversal of 21243300 is 334212.

It is an interprime number because it is at equal distance from previous prime (21243293) and next prime (21243307).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21243300.

It is not an unprimeable number, because it can be changed into a prime (21243307) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 50491 + ... + 50909.

Almost surely, 2^21243300 is an apocalyptic number.

21243300 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 21243300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33357240).

21243300 is an abundant number, since it is smaller than the sum of its proper divisors (45471180).

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

21243300 is a wasteful number, since it uses less digits than its factorization.

21243300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462 (or 442 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21243300 is about 4609.0454543213. The cubic root of 21243300 is about 276.9537994167.

Adding to 21243300 its reverse (334212), we get a palindrome (21577512).

The spelling of 21243300 in words is "twenty-one million, two hundred forty-three thousand, three hundred".