21003600 has 120 divisors (see below), whose sum is σ = 70299072. Its totient is φ = 5350400.

The previous prime is 21003599. The next prime is 21003601. The reversal of 21003600 is 630012.

It is an interprime number because it is at equal distance from previous prime (21003599) and next prime (21003601).

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003601) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27220 + ... + 27980.

Almost surely, 2^21003600 is an apocalyptic number.

21003600 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 21003600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35149536).

21003600 is an abundant number, since it is smaller than the sum of its proper divisors (49295472).

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

21003600 is a wasteful number, since it uses less digits than its factorization.

21003600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805 (or 794 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21003600 is about 4582.9684703258. The cubic root of 21003600 is about 275.9081820183.

Adding to 21003600 its reverse (630012), we get a palindrome (21633612).

The spelling of 21003600 in words is "twenty-one million, three thousand, six hundred".