40397991 has 8 divisors (see below), whose sum is σ = 55601664. Its totient is φ = 26063160.

The previous prime is 40397953. The next prime is 40398013. The reversal of 40397991 is 19979304.

40397991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 40397991 - 2⁹ = 40397479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40397191) 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 7 ways as a sum of consecutive naturals, for example, 217101 + ... + 217286.

It is an arithmetic number, because the mean of its divisors is an integer number (6950208).

Almost surely, 2^40397991 is an apocalyptic number.

40397991 is a deficient number, since it is larger than the sum of its proper divisors (15203673).

40397991 is a wasteful number, since it uses less digits than its factorization.

40397991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434421.

The product of its (nonzero) digits is 61236, while the sum is 42.

The square root of 40397991 is about 6355.9413936883. The cubic root of 40397991 is about 343.1257065158.

The spelling of 40397991 in words is "forty million, three hundred ninety-seven thousand, nine hundred ninety-one".