3998391 has 4 divisors (see below), whose sum is σ = 5331192. Its totient is φ = 2665592.

The previous prime is 3998377. The next prime is 3998399. The reversal of 3998391 is 1938993.

It is a happy number.

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 3998391 - 2⁷ = 3998263 is a prime.

It is a D-number.

3998391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3998399) 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, 666396 + ... + 666401.

It is an arithmetic number, because the mean of its divisors is an integer number (1332798).

Almost surely, 2^3998391 is an apocalyptic number.

3998391 is a deficient number, since it is larger than the sum of its proper divisors (1332801).

3998391 is a wasteful number, since it uses less digits than its factorization.

3998391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1332800.

The product of its digits is 52488, while the sum is 42.

The square root of 3998391 is about 1999.5977095406. The cubic root of 3998391 is about 158.7188179399.

The spelling of 3998391 in words is "three million, nine hundred ninety-eight thousand, three hundred ninety-one".