21240300 has 72 divisors (see below), whose sum is σ = 62152272. Its totient is φ = 5600000.

The previous prime is 21240283. The next prime is 21240311. The reversal of 21240300 is 304212.

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

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, 29950 + ... + 30650.

It is an arithmetic number, because the mean of its divisors is an integer number (863226).

Almost surely, 2^21240300 is an apocalyptic number.

21240300 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 21240300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31076136).

21240300 is an abundant number, since it is smaller than the sum of its proper divisors (40911972).

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

21240300 is a wasteful number, since it uses less digits than its factorization.

21240300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 819 (or 812 counting only the distinct ones).

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

The square root of 21240300 is about 4608.7199958340. The cubic root of 21240300 is about 276.9407615724.

Adding to 21240300 its reverse (304212), we get a palindrome (21544512).

The spelling of 21240300 in words is "twenty-one million, two hundred forty thousand, three hundred".