40391991 has 12 divisors (see below), whose sum is σ = 58418880. Its totient is φ = 26893440.

The previous prime is 40391987. The next prime is 40391993. The reversal of 40391991 is 19919304.

40391991 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 40391991 - 2² = 40391987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40391993) 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 11 ways as a sum of consecutive naturals, for example, 5946 + ... + 10776.

It is an arithmetic number, because the mean of its divisors is an integer number (4868240).

Almost surely, 2^40391991 is an apocalyptic number.

40391991 is a deficient number, since it is larger than the sum of its proper divisors (18026889).

40391991 is a wasteful number, since it uses less digits than its factorization.

40391991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5766 (or 5763 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 40391991 is about 6355.4693768439. The cubic root of 40391991 is about 343.1087184089.

The spelling of 40391991 in words is "forty million, three hundred ninety-one thousand, nine hundred ninety-one".