997998 has 16 divisors (see below), whose sum is σ = 2039040. Its totient is φ = 325496.

The previous prime is 997991. The next prime is 998009. The reversal of 997998 is 899799.

It is a self number, because there is not a number n which added to its sum of digits gives 997998.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 997998.

It is not an unprimeable number, because it can be changed into a prime (997991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1488 + ... + 2051.

It is an arithmetic number, because the mean of its divisors is an integer number (127440).

2⁹⁹⁷⁹⁹⁸ is an apocalyptic number.

997998 is an abundant number, since it is smaller than the sum of its proper divisors (1041042).

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

997998 is a wasteful number, since it uses less digits than its factorization.

997998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3591.

The product of its digits is 367416, while the sum is 51.

The square root of 997998 is about 998.9984984974. The cubic root of 997998 is about 99.9332220837.

The spelling of 997998 in words is "nine hundred ninety-seven thousand, nine hundred ninety-eight".