39121991 has 4 divisors (see below), whose sum is σ = 39206232. Its totient is φ = 39037752.

The previous prime is 39121963. The next prime is 39122023. The reversal of 39121991 is 19912193.

39121991 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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39121991 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 (39121591) 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, 41420 + ... + 42353.

It is an arithmetic number, because the mean of its divisors is an integer number (9801558).

Almost surely, 2^39121991 is an apocalyptic number.

39121991 is a deficient number, since it is larger than the sum of its proper divisors (84241).

39121991 is an equidigital number, since it uses as much as digits as its factorization.

39121991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84240.

The product of its digits is 4374, while the sum is 35.

The square root of 39121991 is about 6254.7574693189. The cubic root of 39121991 is about 339.4743636846.

The spelling of 39121991 in words is "thirty-nine million, one hundred twenty-one thousand, nine hundred ninety-one".