865998 has 64 divisors (see below), whose sum is σ = 2304000. Its totient is φ = 235872.

The previous prime is 865993. The next prime is 866003. The reversal of 865998 is 899568.

It is an interprime number because it is at equal distance from previous prime (865993) and next prime (866003).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

Its product of digits (155520) is a multiple of the sum of its prime divisors (120).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865993) by changing a digit.

865998 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 31 ways as a sum of consecutive naturals, for example, 10923 + ... + 11001.

It is an arithmetic number, because the mean of its divisors is an integer number (36000).

2⁸⁶⁵⁹⁹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 865998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1152000).

865998 is an abundant number, since it is smaller than the sum of its proper divisors (1438002).

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

865998 is a wasteful number, since it uses less digits than its factorization.

865998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126 (or 120 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 865998 is about 930.5901353442. The cubic root of 865998 is about 95.3174238968.

It can be divided in two parts, 86 and 5998, that added together give a square (6084 = 78²).

The spelling of 865998 in words is "eight hundred sixty-five thousand, nine hundred ninety-eight".