3981581939 has 4 divisors (see below), whose sum is σ = 3988014840. Its totient is φ = 3975149040.

The previous prime is 3981581921. The next prime is 3981581963. The reversal of 3981581939 is 9391851893.

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 3981581939 - 2¹² = 3981577843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3981581039) 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, 3215522 + ... + 3216759.

It is an arithmetic number, because the mean of its divisors is an integer number (997003710).

Almost surely, 2^3981581939 is an apocalyptic number.

3981581939 is a deficient number, since it is larger than the sum of its proper divisors (6432901).

3981581939 is an equidigital number, since it uses as much as digits as its factorization.

3981581939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6432900.

The product of its digits is 2099520, while the sum is 56.

The square root of 3981581939 is about 63099.7776462009. Note that the first 3 decimals coincide. The cubic root of 3981581939 is about 1584.9608987690.

The spelling of 3981581939 in words is "three billion, nine hundred eighty-one million, five hundred eighty-one thousand, nine hundred thirty-nine".