811965 has 64 divisors (see below), whose sum is σ = 1751040. Its totient is φ = 311040.

The previous prime is 811961. The next prime is 811981. The reversal of 811965 is 569118.

It is a happy number.

It is not a de Polignac number, because 811965 - 2² = 811961 is a prime.

It is a super-2 number, since 2×811965² = 1318574322450, which contains 22 as substring.

811965 is an undulating number in base 11.

It is a Curzon number.

811965 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811961) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 21927 + ... + 21963.

It is an arithmetic number, because the mean of its divisors is an integer number (27360).

2⁸¹¹⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

811965 is an abundant number, since it is smaller than the sum of its proper divisors (939075).

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

811965 is a wasteful number, since it uses less digits than its factorization.

811965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82.

The product of its digits is 2160, while the sum is 30.

The square root of 811965 is about 901.0910053929. The cubic root of 811965 is about 93.2922934648.

The spelling of 811965 in words is "eight hundred eleven thousand, nine hundred sixty-five".