3991856617 has 8 divisors (see below), whose sum is σ = 4609154816. Its totient is φ = 3386316672.

The previous prime is 3991856587. The next prime is 3991856621. The reversal of 3991856617 is 7166581993.

It is a happy number.

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 3991856617 - 2¹¹ = 3991854569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3991856657) 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, 2938833 + ... + 2940190.

It is an arithmetic number, because the mean of its divisors is an integer number (576144352).

Almost surely, 2^3991856617 is an apocalyptic number.

It is an amenable number.

3991856617 is a deficient number, since it is larger than the sum of its proper divisors (617298199).

3991856617 is an equidigital number, since it uses as much as digits as its factorization.

3991856617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5879127.

The product of its digits is 2449440, while the sum is 55.

The square root of 3991856617 is about 63181.1413081467. The cubic root of 3991856617 is about 1586.3230855507.

The spelling of 3991856617 in words is "three billion, nine hundred ninety-one million, eight hundred fifty-six thousand, six hundred seventeen".