21781872000 has 960 divisors, whose sum is σ = 94380755040. Its totient is φ = 4978713600.

The previous prime is 21781871963. The next prime is 21781872037. The reversal of 21781872000 is 27818712.

It is a happy number.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is an interprime number because it is at equal distance from previous prime (21781871963) and next prime (21781872037).

It is a tau number, because it is divible by the number of its divisors (960).

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 119 ways as a sum of consecutive naturals, for example, 3111695997 + ... + 3111696003.

Almost surely, 2^21781872000 is an apocalyptic number.

21781872000 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 21781872000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47190377520).

21781872000 is an abundant number, since it is smaller than the sum of its proper divisors (72598883040).

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

21781872000 is an frugal number, since it uses more digits than its factorization.

21781872000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 17 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The spelling of 21781872000 in words is "twenty-one billion, seven hundred eighty-one million, eight hundred seventy-two thousand".