3981916185491 has 4 divisors (see below), whose sum is σ = 3981925068312. Its totient is φ = 3981907302672.

The previous prime is 3981916185469. The next prime is 3981916185557. The reversal of 3981916185491 is 1945816191893.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 3981916185491 - 2¹⁴ = 3981916169107 is a prime.

It is a super-2 number, since 2×3981916185491² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3981916185451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3731141 + ... + 4678166.

It is an arithmetic number, because the mean of its divisors is an integer number (995481267078).

Almost surely, 2^{3981916185491} is an apocalyptic number.

3981916185491 is a deficient number, since it is larger than the sum of its proper divisors (8882821).

3981916185491 is an equidigital number, since it uses as much as digits as its factorization.

3981916185491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8882820.

The product of its digits is 16796160, while the sum is 65.

The spelling of 3981916185491 in words is "three trillion, nine hundred eighty-one billion, nine hundred sixteen million, one hundred eighty-five thousand, four hundred ninety-one".