3991917 has 8 divisors (see below), whose sum is σ = 5382720. Its totient is φ = 2631200.

The previous prime is 3991891. The next prime is 3991943. The reversal of 3991917 is 7191993.

It is an interprime number because it is at equal distance from previous prime (3991891) and next prime (3991943).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 3991917 - 2⁶ = 3991853 is a prime.

3991917 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991997) 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, 7209 + ... + 7742.

It is an arithmetic number, because the mean of its divisors is an integer number (672840).

Almost surely, 2^3991917 is an apocalyptic number.

It is an amenable number.

3991917 is a deficient number, since it is larger than the sum of its proper divisors (1390803).

3991917 is a wasteful number, since it uses less digits than its factorization.

3991917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15043.

The product of its digits is 15309, while the sum is 39.

The square root of 3991917 is about 1997.9782281096. The cubic root of 3991917 is about 158.6331084040.

The spelling of 3991917 in words is "three million, nine hundred ninety-one thousand, nine hundred seventeen".