811205120 has 80 divisors (see below), whose sum is σ = 2121882048. Its totient is φ = 294973440.

The previous prime is 811205051. The next prime is 811205123. The reversal of 811205120 is 21502118.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 811205092 and 811205101.

It is not an unprimeable number, because it can be changed into a prime (811205123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13757 + ... + 42563.

Almost surely, 2^811205120 is an apocalyptic number.

811205120 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 811205120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1060941024).

811205120 is an abundant number, since it is smaller than the sum of its proper divisors (1310676928).

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

811205120 is a wasteful number, since it uses less digits than its factorization.

811205120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28841 (or 28825 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 811205120 is about 28481.6628728029. The cubic root of 811205120 is about 932.6318175271.

Adding to 811205120 its reverse (21502118), we get a palindrome (832707238).

The spelling of 811205120 in words is "eight hundred eleven million, two hundred five thousand, one hundred twenty".