43540991 has 6 divisors (see below), whose sum is σ = 47148120. Its totient is φ = 40191528.

The previous prime is 43540969. The next prime is 43541009. The reversal of 43540991 is 19904534.

It is not a de Polignac number, because 43540991 - 2¹⁰ = 43539967 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 (43540291) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 128651 + ... + 128988.

It is an arithmetic number, because the mean of its divisors is an integer number (7858020).

Almost surely, 2^43540991 is an apocalyptic number.

43540991 is a deficient number, since it is larger than the sum of its proper divisors (3607129).

43540991 is a wasteful number, since it uses less digits than its factorization.

43540991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257665 (or 257652 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 43540991 is about 6598.5597671007. The cubic root of 43540991 is about 351.8029172879.

The spelling of 43540991 in words is "forty-three million, five hundred forty thousand, nine hundred ninety-one".