21243787200 has 252 divisors, whose sum is σ = 75711029680. Its totient is φ = 5649592320.

The previous prime is 21243787199. The next prime is 21243787219. The reversal of 21243787200 is 278734212.

21243787200 is a `hidden beast` number, since 2 + 12 + 437 + 8 + 7 + 200 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5887797 + ... + 5891403.

Almost surely, 2^21243787200 is an apocalyptic number.

21243787200 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 21243787200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37855514840).

21243787200 is an abundant number, since it is smaller than the sum of its proper divisors (54467242480).

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

21243787200 is a wasteful number, since it uses less digits than its factorization.

21243787200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4044 (or 4026 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 36.

The spelling of 21243787200 in words is "twenty-one billion, two hundred forty-three million, seven hundred eighty-seven thousand, two hundred".