21720223816704 has 2816 divisors, whose sum is σ = 86061314211840. Its totient is φ = 5264674652160.

The previous prime is 21720223816693. The next prime is 21720223816729. The reversal of 21720223816704 is 40761832202712.

21720223816704 is a `hidden beast` number, since 2 + 1 + 7 + 202 + 2 + 381 + 67 + 0 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21720223816704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 110254943134 + ... + 110254943330.

It is an arithmetic number, because the mean of its divisors is an integer number (30561546240).

Almost surely, 2^{21720223816704} is an apocalyptic number.

21720223816704 is a gapful number since it is divisible by the number (24) 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 21720223816704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43030657105920).

21720223816704 is an abundant number, since it is smaller than the sum of its proper divisors (64341090395136).

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

21720223816704 is a wasteful number, since it uses less digits than its factorization.

21720223816704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351 (or 327 counting only the distinct ones).

The product of its (nonzero) digits is 451584, while the sum is 45.

The spelling of 21720223816704 in words is "twenty-one trillion, seven hundred twenty billion, two hundred twenty-three million, eight hundred sixteen thousand, seven hundred four".