91041991 has 4 divisors (see below), whose sum is σ = 94181400. Its totient is φ = 87902584.

The previous prime is 91041983. The next prime is 91042013. The reversal of 91041991 is 19914019.

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 91041991 - 2³ = 91041983 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 (91041911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1569661 + ... + 1569718.

It is an arithmetic number, because the mean of its divisors is an integer number (23545350).

Almost surely, 2^91041991 is an apocalyptic number.

91041991 is a deficient number, since it is larger than the sum of its proper divisors (3139409).

91041991 is a wasteful number, since it uses less digits than its factorization.

91041991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3139408.

The product of its (nonzero) digits is 2916, while the sum is 34.

The square root of 91041991 is about 9541.5926867583. The cubic root of 91041991 is about 449.8633181596.

The spelling of 91041991 in words is "ninety-one million, forty-one thousand, nine hundred ninety-one".