815864 has 32 divisors (see below), whose sum is σ = 1853280. Its totient is φ = 328704.

The previous prime is 815851. The next prime is 815869. The reversal of 815864 is 468518.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 815864.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815869) by changing a digit.

815864 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 7 ways as a sum of consecutive naturals, for example, 524 + ... + 1380.

It is an arithmetic number, because the mean of its divisors is an integer number (57915).

2⁸¹⁵⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 815864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (926640).

815864 is an abundant number, since it is smaller than the sum of its proper divisors (1037416).

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

815864 is a wasteful number, since it uses less digits than its factorization.

815864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 887 (or 883 counting only the distinct ones).

The product of its digits is 7680, while the sum is 32.

The square root of 815864 is about 903.2519028488. The cubic root of 815864 is about 93.4413828023.

The spelling of 815864 in words is "eight hundred fifteen thousand, eight hundred sixty-four".