3991607656 has 32 divisors (see below), whose sum is σ = 7831601640. Its totient is φ = 1905216768.

The previous prime is 3991607639. The next prime is 3991607663. The reversal of 3991607656 is 6567061993.

It can be written as a sum of positive squares in 4 ways, for example, as 3620428900 + 371178756 = 60170^2 + 19266^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111531 + ... + 142906.

Almost surely, 2^3991607656 is an apocalyptic number.

It is an amenable number.

3991607656 is a deficient number, since it is larger than the sum of its proper divisors (3839993984).

3991607656 is a wasteful number, since it uses less digits than its factorization.

3991607656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254533 (or 254529 counting only the distinct ones).

The product of its (nonzero) digits is 1837080, while the sum is 52.

The square root of 3991607656 is about 63179.1710613553. The cubic root of 3991607656 is about 1586.2901066781.

The spelling of 3991607656 in words is "three billion, nine hundred ninety-one million, six hundred seven thousand, six hundred fifty-six".