91991901 has 16 divisors (see below), whose sum is σ = 129521600. Its totient is φ = 57915648.

The previous prime is 91991891. The next prime is 91991917. The reversal of 91991901 is 10919919.

It is not a de Polignac number, because 91991901 - 2¹⁴ = 91975517 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91991901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91991951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16815 + ... + 21603.

It is an arithmetic number, because the mean of its divisors is an integer number (8095100).

Almost surely, 2^91991901 is an apocalyptic number.

It is an amenable number.

91991901 is a deficient number, since it is larger than the sum of its proper divisors (37529699).

91991901 is a wasteful number, since it uses less digits than its factorization.

91991901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5148.

The product of its (nonzero) digits is 6561, while the sum is 39.

The square root of 91991901 is about 9591.2408477736. The cubic root of 91991901 is about 451.4224961366.

The spelling of 91991901 in words is "ninety-one million, nine hundred ninety-one thousand, nine hundred one".