21073917920 has 96 divisors (see below), whose sum is σ = 54647187840. Its totient is φ = 7616125440.

The previous prime is 21073917919. The next prime is 21073917947. The reversal of 21073917920 is 2971937012.

It is a super-2 number, since 2×21073917920² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 250151 + ... + 323609.

It is an arithmetic number, because the mean of its divisors is an integer number (569241540).

Almost surely, 2^21073917920 is an apocalyptic number.

21073917920 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 21073917920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27323593920).

21073917920 is an abundant number, since it is smaller than the sum of its proper divisors (33573269920).

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

21073917920 is a wasteful number, since it uses less digits than its factorization.

21073917920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73648 (or 73640 counting only the distinct ones).

The product of its (nonzero) digits is 47628, while the sum is 41.

The spelling of 21073917920 in words is "twenty-one billion, seventy-three million, nine hundred seventeen thousand, nine hundred twenty".