865440 has 72 divisors (see below), whose sum is σ = 2958228. Its totient is φ = 230400.

The previous prime is 865409. The next prime is 865457. The reversal of 865440 is 44568.

865440 is a `hidden beast` number, since 8 + 654 + 4 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 853776 + 11664 = 924^2 + 108^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a nialpdrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 865440.

It is an unprimeable number.

865440 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 11 ways as a sum of consecutive naturals, for example, 1140 + ... + 1740.

2⁸⁶⁵⁴⁴⁰ is an apocalyptic number.

865440 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 865440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1479114).

865440 is an abundant number, since it is smaller than the sum of its proper divisors (2092788).

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

865440 is a wasteful number, since it uses less digits than its factorization.

865440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622 (or 611 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 865440 is about 930.2902772791. The cubic root of 865440 is about 95.2969471174.

The spelling of 865440 in words is "eight hundred sixty-five thousand, four hundred forty".