3981536021 has 4 divisors (see below), whose sum is σ = 3982339392. Its totient is φ = 3980732652.

The previous prime is 3981535919. The next prime is 3981536033. The reversal of 3981536021 is 1206351893.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1206351893 = 271 ⋅4451483.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3981536021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3981532021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 394205 + ... + 404178.

It is an arithmetic number, because the mean of its divisors is an integer number (995584848).

Almost surely, 2^3981536021 is an apocalyptic number.

It is an amenable number.

3981536021 is a deficient number, since it is larger than the sum of its proper divisors (803371).

3981536021 is an equidigital number, since it uses as much as digits as its factorization.

3981536021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 803370.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 3981536021 is about 63099.4137928396. The cubic root of 3981536021 is about 1584.9548058378.

The spelling of 3981536021 in words is "three billion, nine hundred eighty-one million, five hundred thirty-six thousand, twenty-one".