21405300 has 72 divisors (see below), whose sum is σ = 70787136. Its totient is φ = 4892160.

The previous prime is 21405299. The next prime is 21405313. The reversal of 21405300 is 350412.

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 21405300.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2997 + ... + 7196.

Almost surely, 2^21405300 is an apocalyptic number.

21405300 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21405300 is an abundant number, since it is smaller than the sum of its proper divisors (49381836).

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

21405300 is a wasteful number, since it uses less digits than its factorization.

21405300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10217 (or 10210 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21405300 is about 4626.5862144782. The cubic root of 21405300 is about 277.6560278300.

Adding to 21405300 its reverse (350412), we get a palindrome (21755712).

The spelling of 21405300 in words is "twenty-one million, four hundred five thousand, three hundred".