997999 has 4 divisors (see below), whose sum is σ = 1001520. Its totient is φ = 994480.

The previous prime is 997991. The next prime is 998009. The reversal of 997999 is 999799.

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

It is a cyclic number.

It is not a de Polignac number, because 997999 - 2³ = 997991 is a prime.

It is a Duffinian number.

997999 is a modest number, since divided by 999 gives 997 as remainder.

997999 is a lucky number.

It is a congruent number.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1294 + ... + 1915.

It is an arithmetic number, because the mean of its divisors is an integer number (250380).

2⁹⁹⁷⁹⁹⁹ is an apocalyptic number.

997999 is a deficient number, since it is larger than the sum of its proper divisors (3521).

997999 is a wasteful number, since it uses less digits than its factorization.

997999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3520.

The product of its digits is 413343, while the sum is 52.

The square root of 997999 is about 998.9989989985. The cubic root of 997999 is about 99.9332554616.

The spelling of 997999 in words is "nine hundred ninety-seven thousand, nine hundred ninety-nine".