3991998 has 16 divisors (see below), whose sum is σ = 8015616. Its totient is φ = 1325400.

The previous prime is 3991997. The next prime is 3992011. The reversal of 3991998 is 8991993.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 523 + ... + 2873.

It is an arithmetic number, because the mean of its divisors is an integer number (500976).

Almost surely, 2^3991998 is an apocalyptic number.

3991998 is an abundant number, since it is smaller than the sum of its proper divisors (4023618).

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

3991998 is a wasteful number, since it uses less digits than its factorization.

3991998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2639.

The product of its digits is 157464, while the sum is 48.

The square root of 3991998 is about 1997.9984984979. The cubic root of 3991998 is about 158.6341813383.

The spelling of 3991998 in words is "three million, nine hundred ninety-one thousand, nine hundred ninety-eight".