39491981 has 4 divisors (see below), whose sum is σ = 39967872. Its totient is φ = 39016092.

The previous prime is 39491971. The next prime is 39491983. The reversal of 39491981 is 18919493.

39491981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 39491981 - 2⁶ = 39491917 is a prime.

It is a super-2 number, since 2×39491981² = 3119233126608722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39491983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 237821 + ... + 237986.

It is an arithmetic number, because the mean of its divisors is an integer number (9991968).

Almost surely, 2^39491981 is an apocalyptic number.

It is an amenable number.

39491981 is a deficient number, since it is larger than the sum of its proper divisors (475891).

39491981 is an equidigital number, since it uses as much as digits as its factorization.

39491981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475890.

The product of its digits is 69984, while the sum is 44.

The square root of 39491981 is about 6284.2645552204. The cubic root of 39491981 is about 340.5411825415.

The spelling of 39491981 in words is "thirty-nine million, four hundred ninety-one thousand, nine hundred eighty-one".