3991643537 has 48 divisors (see below), whose sum is σ = 5228364672. Its totient is φ = 3021258240.

The previous prime is 3991643477. The next prime is 3991643543. The reversal of 3991643537 is 7353461993.

It is not a de Polignac number, because 3991643537 - 2²² = 3987449233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3991643567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1013462 + ... + 1017392.

It is an arithmetic number, because the mean of its divisors is an integer number (108924264).

Almost surely, 2^3991643537 is an apocalyptic number.

It is an amenable number.

3991643537 is a deficient number, since it is larger than the sum of its proper divisors (1236721135).

3991643537 is a wasteful number, since it uses less digits than its factorization.

3991643537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4038 (or 4031 counting only the distinct ones).

The product of its digits is 1837080, while the sum is 50.

The square root of 3991643537 is about 63179.4550229740. The cubic root of 3991643537 is about 1586.2948597760.

The spelling of 3991643537 in words is "three billion, nine hundred ninety-one million, six hundred forty-three thousand, five hundred thirty-seven".