3998 has 4 divisors (see below), whose sum is σ = 6000. Its totient is φ = 1998.

The previous prime is 3989. The next prime is 4001. The reversal of 3998 is 8993.

3998 is nontrivially palindromic in base 7.

3998 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It is a nialpdrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 3998.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 998 + ... + 1001.

It is an arithmetic number, because the mean of its divisors is an integer number (1500).

2³⁹⁹⁸ is an apocalyptic number.

3998 is a deficient number, since it is larger than the sum of its proper divisors (2002).

3998 is a wasteful number, since it uses less digits than its factorization.

3998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2001.

The product of its digits is 1944, while the sum is 29.

The square root of 3998 is about 63.2297398381. The cubic root of 3998 is about 15.8713644102.

Subtracting from 3998 its sum of digits (29), we obtain a square (3969 = 63²).

It can be divided in two parts, 3 and 998, that added together give a palindrome (1001).

The spelling of 3998 in words is "three thousand, nine hundred ninety-eight".