3991681918323 has 168 divisors, whose sum is σ = 6989574110400. Its totient is φ = 2270353393440.

The previous prime is 3991681918253. The next prime is 3991681918397. The reversal of 3991681918323 is 3238191861993.

3991681918323 is a `hidden beast` number, since 39 + 91 + 6 + 8 + 191 + 8 + 323 = 666.

It is not a de Polignac number, because 3991681918323 - 2⁸ = 3991681918067 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3991681918823) by changing a digit.

It is a polite number, since it can be written in 167 ways as a sum of consecutive naturals, for example, 179317768 + ... + 179340026.

It is an arithmetic number, because the mean of its divisors is an integer number (41604607800).

Almost surely, 2^{3991681918323} is an apocalyptic number.

3991681918323 is a gapful number since it is divisible by the number (33) formed by its first and last digit.

3991681918323 is a deficient number, since it is larger than the sum of its proper divisors (2997892192077).

3991681918323 is a wasteful number, since it uses less digits than its factorization.

3991681918323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22425 (or 22399 counting only the distinct ones).

The product of its digits is 15116544, while the sum is 63.

The spelling of 3991681918323 in words is "three trillion, nine hundred ninety-one billion, six hundred eighty-one million, nine hundred eighteen thousand, three hundred twenty-three".