21084942720 has 256 divisors, whose sum is σ = 70375495680. Its totient is φ = 5359411200.

The previous prime is 21084942707. The next prime is 21084942727. The reversal of 21084942720 is 2724948012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21084942727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16206070 + ... + 16207370.

It is an arithmetic number, because the mean of its divisors is an integer number (274904280).

Almost surely, 2^21084942720 is an apocalyptic number.

21084942720 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 21084942720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35187747840).

21084942720 is an abundant number, since it is smaller than the sum of its proper divisors (49290552960).

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

21084942720 is a wasteful number, since it uses less digits than its factorization.

21084942720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1713 (or 1701 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 39.

The spelling of 21084942720 in words is "twenty-one billion, eighty-four million, nine hundred forty-two thousand, seven hundred twenty".