9781998 has 32 divisors (see below), whose sum is σ = 20995200. Its totient is φ = 3028896.

The previous prime is 9781997. The next prime is 9782011. The reversal of 9781998 is 8991879.

9781998 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 9781998.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9781991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5233 + ... + 6851.

It is an arithmetic number, because the mean of its divisors is an integer number (656100).

Almost surely, 2^9781998 is an apocalyptic number.

9781998 is an abundant number, since it is smaller than the sum of its proper divisors (11213202).

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

9781998 is a wasteful number, since it uses less digits than its factorization.

9781998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696.

The product of its digits is 326592, while the sum is 51.

The square root of 9781998 is about 3127.6185828838. The cubic root of 9781998 is about 213.8663823647.

The spelling of 9781998 in words is "nine million, seven hundred eighty-one thousand, nine hundred ninety-eight".