3991487636 has 12 divisors (see below), whose sum is σ = 7011072180. Its totient is φ = 1988324160.

The previous prime is 3991487627. The next prime is 3991487639. The reversal of 3991487636 is 6367841993.

3991487636 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 365039236 + 3626448400 = 19106^2 + 60220^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991487639) 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, 1853705 + ... + 1855856.

It is an arithmetic number, because the mean of its divisors is an integer number (584256015).

Almost surely, 2^3991487636 is an apocalyptic number.

It is an amenable number.

3991487636 is a deficient number, since it is larger than the sum of its proper divisors (3019584544).

3991487636 is a wasteful number, since it uses less digits than its factorization.

3991487636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3709834 (or 3709832 counting only the distinct ones).

The product of its digits is 5878656, while the sum is 56.

The square root of 3991487636 is about 63178.2212158589. The cubic root of 3991487636 is about 1586.2742076166.

The spelling of 3991487636 in words is "three billion, nine hundred ninety-one million, four hundred eighty-seven thousand, six hundred thirty-six".