81920000 has 90 divisors (see below), whose sum is σ = 204733683. Its totient is φ = 32768000.

The previous prime is 81919993. The next prime is 81920021. The reversal of 81920000 is 2918.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 3 ways, for example, as 18939904 + 62980096 = 4352^2 + 7936^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=6400.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 4 ways as a sum of consecutive naturals, for example, 16383998 + ... + 16384002.

Almost surely, 2^81920000 is an apocalyptic number.

81920000 is a gapful number since it is divisible by the number (80) 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 81920000

81920000 is an abundant number, since it is smaller than the sum of its proper divisors (122813683).

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

81920000 is an frugal number, since it uses more digits than its factorization.

81920000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54 (or 7 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 81920000 is about 9050.9667991878. The cubic root of 81920000 is about 434.3068186552.

81920000 divided by its sum of digits (20) gives a cube (4096000 = 160³).

Adding to 81920000 its reverse (2918), we get a palindrome (81922918).

The spelling of 81920000 in words is "eighty-one million, nine hundred twenty thousand".