21045300 has 144 divisors (see below), whose sum is σ = 65620800. Its totient is φ = 5196800.

The previous prime is 21045287. The next prime is 21045301. The reversal of 21045300 is 354012.

21045300 = T₁₃₆ + T₁₃₇ + ... + T₅₀₄.

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 21045300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 356671 + ... + 356729.

It is an arithmetic number, because the mean of its divisors is an integer number (455700).

Almost surely, 2^21045300 is an apocalyptic number.

21045300 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 21045300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32810400).

21045300 is an abundant number, since it is smaller than the sum of its proper divisors (44575500).

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

21045300 is a wasteful number, since it uses less digits than its factorization.

21045300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 139 counting only the distinct ones).

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

The square root of 21045300 is about 4587.5156675482. The cubic root of 21045300 is about 276.0906549503.

Adding to 21045300 its reverse (354012), we get a palindrome (21399312).

The spelling of 21045300 in words is "twenty-one million, forty-five thousand, three hundred".