40043991 has 16 divisors (see below), whose sum is σ = 58586976. Its totient is φ = 24176256.

The previous prime is 40043981. The next prime is 40044013. The reversal of 40043991 is 19934004.

40043991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 40043991 - 2⁷ = 40043863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40043981) 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 15 ways as a sum of consecutive naturals, for example, 7620 + ... + 11753.

It is an arithmetic number, because the mean of its divisors is an integer number (3661686).

Almost surely, 2^40043991 is an apocalyptic number.

40043991 is a deficient number, since it is larger than the sum of its proper divisors (18542985).

40043991 is a wasteful number, since it uses less digits than its factorization.

40043991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19442.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 40043991 is about 6328.0321585782. The cubic root of 40043991 is about 342.1205159893.

Adding to 40043991 its reverse (19934004), we get a palindrome (59977995).

The spelling of 40043991 in words is "forty million, forty-three thousand, nine hundred ninety-one".