809889840 has 180 divisors, whose sum is σ = 2826177744. Its totient is φ = 215830656.

The previous prime is 809889833. The next prime is 809889923. The reversal of 809889840 is 48988908.

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (54).

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 35 ways as a sum of consecutive naturals, for example, 524109 + ... + 525651.

Almost surely, 2^809889840 is an apocalyptic number.

809889840 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 809889840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1413088872).

809889840 is an abundant number, since it is smaller than the sum of its proper divisors (2016287904).

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

809889840 is an equidigital number, since it uses as much as digits as its factorization.

809889840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1580 (or 1553 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 54.

The square root of 809889840 is about 28458.5635617822. The cubic root of 809889840 is about 932.1274915082.

The spelling of 809889840 in words is "eight hundred nine million, eight hundred eighty-nine thousand, eight hundred forty".