81485920 has 24 divisors (see below), whose sum is σ = 192510864. Its totient is φ = 32594304.

The previous prime is 81485897. The next prime is 81485933. The reversal of 81485920 is 2958418.

It is a self number, because there is not a number n which added to its sum of digits gives 81485920.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 254484 + ... + 254803.

It is an arithmetic number, because the mean of its divisors is an integer number (8021286).

Almost surely, 2^81485920 is an apocalyptic number.

81485920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81485920 is an abundant number, since it is smaller than the sum of its proper divisors (111024944).

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

81485920 is a wasteful number, since it uses less digits than its factorization.

81485920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509302 (or 509294 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 81485920 is about 9026.9551898744. The cubic root of 81485920 is about 433.5383540034.

The spelling of 81485920 in words is "eighty-one million, four hundred eighty-five thousand, nine hundred twenty".