21084354720 has 1152 divisors, whose sum is σ = 94509192960. Its totient is φ = 4193648640.

The previous prime is 21084354713. The next prime is 21084354761. The reversal of 21084354720 is 2745348012.

It is a happy number.

21084354720 is a `hidden beast` number, since 2 + 10 + 84 + 3 + 547 + 20 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 66512002 + ... + 66512318.

It is an arithmetic number, because the mean of its divisors is an integer number (82039230).

Almost surely, 2^21084354720 is an apocalyptic number.

21084354720 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 21084354720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47254596480).

21084354720 is an abundant number, since it is smaller than the sum of its proper divisors (73424838240).

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

21084354720 is a wasteful number, since it uses less digits than its factorization.

21084354720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398 (or 387 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 36.

The spelling of 21084354720 in words is "twenty-one billion, eighty-four million, three hundred fifty-four thousand, seven hundred twenty".