40397891 has 4 divisors (see below), whose sum is σ = 40485984. Its totient is φ = 40309800.

The previous prime is 40397887. The next prime is 40397909. The reversal of 40397891 is 19879304.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 40397891 - 2² = 40397887 is a prime.

It is a Duffinian 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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43355 + ... + 44276.

It is an arithmetic number, because the mean of its divisors is an integer number (10121496).

Almost surely, 2^40397891 is an apocalyptic number.

40397891 is a deficient number, since it is larger than the sum of its proper divisors (88093).

40397891 is an equidigital number, since it uses as much as digits as its factorization.

40397891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88092.

The product of its (nonzero) digits is 54432, while the sum is 41.

The square root of 40397891 is about 6355.9335270281. The cubic root of 40397891 is about 343.1254233944.

The spelling of 40397891 in words is "forty million, three hundred ninety-seven thousand, eight hundred ninety-one".