81428320 has 48 divisors (see below), whose sum is σ = 198592128. Its totient is φ = 31518720.

The previous prime is 81428309. The next prime is 81428323. The reversal of 81428320 is 2382418.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81428323) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3249 + ... + 13168.

It is an arithmetic number, because the mean of its divisors is an integer number (4137336).

Almost surely, 2^81428320 is an apocalyptic number.

81428320 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81428320 is an abundant number, since it is smaller than the sum of its proper divisors (117163808).

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

81428320 is a wasteful number, since it uses less digits than its factorization.

81428320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16463 (or 16455 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 81428320 is about 9023.7641813159. The cubic root of 81428320 is about 433.4361780879.

The spelling of 81428320 in words is "eighty-one million, four hundred twenty-eight thousand, three hundred twenty".