21945600 has 216 divisors, whose sum is σ = 81105920. Its totient is φ = 5806080.

The previous prime is 21945587. The next prime is 21945601. The reversal of 21945600 is 654912.

21945600 is a `hidden beast` number, since 2 + 19 + 45 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945601) by changing a digit.

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, 172737 + ... + 172863.

Almost surely, 2^21945600 is an apocalyptic number.

21945600 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 21945600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40552960).

21945600 is an abundant number, since it is smaller than the sum of its proper divisors (59160320).

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

21945600 is a wasteful number, since it uses less digits than its factorization.

21945600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21945600 is about 4684.6131110264. The cubic root of 21945600 is about 279.9727864708.

The spelling of 21945600 in words is "twenty-one million, nine hundred forty-five thousand, six hundred".