3997 has 4 divisors (see below), whose sum is σ = 4576. Its totient is φ = 3420.

The previous prime is 3989. The next prime is 4001. The reversal of 3997 is 7993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 3997 - 2³ = 3989 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3907) 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, 279 + ... + 292.

It is an arithmetic number, because the mean of its divisors is an integer number (1144).

3997 is the 37-th hex number.

It is an amenable number.

3997 is a deficient number, since it is larger than the sum of its proper divisors (579).

3997 is an equidigital number, since it uses as much as digits as its factorization.

3997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578.

The product of its digits is 1701, while the sum is 28.

The square root of 3997 is about 63.2218316723. The cubic root of 3997 is about 15.8700410245.

Subtracting from 3997 its sum of digits (28), we obtain a square (3969 = 63²).

Multiplying 3997 by its reverse (7993), we get a triangular number (31948021 = T₇₉₉₃).

It can be divided in two parts, 399 and 7, that added together give a triangular number (406 = T₂₈).

The spelling of 3997 in words is "three thousand, nine hundred ninety-seven".