81920020 has 192 divisors, whose sum is σ = 234823680. Its totient is φ = 23265792.

The previous prime is 81919993. The next prime is 81920021. The reversal of 81920020 is 2002918.

It is a junction number, because it is equal to n+sod(n) for n = 81919973 and 81920000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81920021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 795289 + ... + 795391.

It is an arithmetic number, because the mean of its divisors is an integer number (1223040).

Almost surely, 2^81920020 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81920020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117411840).

81920020 is an abundant number, since it is smaller than the sum of its proper divisors (152903660).

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

81920020 is a wasteful number, since it uses less digits than its factorization.

81920020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 81920020 is about 9050.9679040421. The cubic root of 81920020 is about 434.3068539992.

Adding to 81920020 its reverse (2002918), we get a palindrome (83922938).

The spelling of 81920020 in words is "eighty-one million, nine hundred twenty thousand, twenty".