809408640 has 128 divisors (see below), whose sum is σ = 2692310400. Its totient is φ = 206446592.

The previous prime is 809408627. The next prime is 809408657. The reversal of 809408640 is 46804908.

It is a tau number, because it is divible by the number of its divisors (128).

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 15 ways as a sum of consecutive naturals, for example, 34996 + ... + 53324.

It is an arithmetic number, because the mean of its divisors is an integer number (21033675).

Almost surely, 2^809408640 is an apocalyptic number.

809408640 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 809408640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1346155200).

809408640 is an abundant number, since it is smaller than the sum of its proper divisors (1882901760).

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

809408640 is a wasteful number, since it uses less digits than its factorization.

809408640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18374 (or 18362 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The square root of 809408640 is about 28450.1079084070. The cubic root of 809408640 is about 931.9428455683.

The spelling of 809408640 in words is "eight hundred nine million, four hundred eight thousand, six hundred forty".