809121280 has 160 divisors (see below), whose sum is σ = 2156647680. Its totient is φ = 288645120.

The previous prime is 809121259. The next prime is 809121281. The reversal of 809121280 is 82121908.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (160).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (809121281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1661197 + ... + 1661683.

It is an arithmetic number, because the mean of its divisors is an integer number (13479048).

Almost surely, 2^809121280 is an apocalyptic number.

809121280 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 809121280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1078323840).

809121280 is an abundant number, since it is smaller than the sum of its proper divisors (1347526400).

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

809121280 is a wasteful number, since it uses less digits than its factorization.

809121280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 580 (or 564 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 809121280 is about 28445.0572156218. The cubic root of 809121280 is about 931.8325449606.

The spelling of 809121280 in words is "eight hundred nine million, one hundred twenty-one thousand, two hundred eighty".