21603600 has 180 divisors, whose sum is σ = 79605396. Its totient is φ = 5406720.

The previous prime is 21603599. The next prime is 21603607. The reversal of 21603600 is 630612.

It is a happy number.

21603600 is a `hidden beast` number, since 2 + 1 + 60 + 3 + 600 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 36864 + 21566736 = 192^2 + 4644^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Saint-Exupery number, since it is equal to the product of the sides of a Pythagorean triangle: 353 × 225 × 272.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21603607) 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, 61024 + ... + 61376.

Almost surely, 2^21603600 is an apocalyptic number.

21603600 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 21603600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39802698).

21603600 is an abundant number, since it is smaller than the sum of its proper divisors (58001796).

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

21603600 is a wasteful number, since it uses less digits than its factorization.

21603600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 380 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21603600 is about 4647.9672976474. The cubic root of 21603600 is about 278.5108011201.

The spelling of 21603600 in words is "twenty-one million, six hundred three thousand, six hundred".