811440 has 180 divisors, whose sum is σ = 3307824. Its totient is φ = 177408.

The previous prime is 811429. The next prime is 811441. The reversal of 811440 is 44118.

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 (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 811440.

It is not an unprimeable number, because it can be changed into a prime (811441) by changing a digit.

811440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 35269 + ... + 35291.

2⁸¹¹⁴⁴⁰ is an apocalyptic number.

811440 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 811440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1653912).

811440 is an abundant number, since it is smaller than the sum of its proper divisors (2496384).

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

811440 is a wasteful number, since it uses less digits than its factorization.

811440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 811440 is about 900.7996447601. The cubic root of 811440 is about 93.2721821653.

Adding to 811440 its reverse (44118), we get a palindrome (855558).

It can be divided in two parts, 81 and 1440, that added together give a square (1521 = 39²).

The spelling of 811440 in words is "eight hundred eleven thousand, four hundred forty".