999855 has 24 divisors (see below), whose sum is σ = 1836432. Its totient is φ = 501504.

The previous prime is 999853. The next prime is 999863. The reversal of 999855 is 558999.

It is not a de Polignac number, because 999855 - 2¹ = 999853 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 999855.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999853) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 112 + ... + 1418.

It is an arithmetic number, because the mean of its divisors is an integer number (76518).

2⁹⁹⁹⁸⁵⁵ is an apocalyptic number.

999855 is a deficient number, since it is larger than the sum of its proper divisors (836577).

999855 is a wasteful number, since it uses less digits than its factorization.

999855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1335 (or 1332 counting only the distinct ones).

The product of its digits is 145800, while the sum is 45.

The square root of 999855 is about 999.9274973717. The cubic root of 999855 is about 99.9951664330.

The spelling of 999855 in words is "nine hundred ninety-nine thousand, eight hundred fifty-five".