3991985849 has 8 divisors (see below), whose sum is σ = 4228617960. Its totient is φ = 3755554816.

The previous prime is 3991985779. The next prime is 3991985867. The reversal of 3991985849 is 9485891993.

It can be written as a sum of positive squares in 4 ways, for example, as 108826624 + 3883159225 = 10432^2 + 62315^2 .

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 3991985849 - 2¹² = 3991981753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3991685849) 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, 8384 + ... + 89745.

It is an arithmetic number, because the mean of its divisors is an integer number (528577245).

Almost surely, 2^3991985849 is an apocalyptic number.

It is an amenable number.

3991985849 is a deficient number, since it is larger than the sum of its proper divisors (236632111).

3991985849 is a wasteful number, since it uses less digits than its factorization.

3991985849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100539.

The product of its digits is 25194240, while the sum is 65.

The square root of 3991985849 is about 63182.1640101065. The cubic root of 3991985849 is about 1586.3402038587.

The spelling of 3991985849 in words is "three billion, nine hundred ninety-one million, nine hundred eighty-five thousand, eight hundred forty-nine".