91109921 has 16 divisors (see below), whose sum is σ = 110002560. Its totient is φ = 73716480.

The previous prime is 91109917. The next prime is 91109933. The reversal of 91109921 is 12990119.

It is a cyclic number.

It is not a de Polignac number, because 91109921 - 2² = 91109917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91109951) 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 15 ways as a sum of consecutive naturals, for example, 41081 + ... + 43241.

It is an arithmetic number, because the mean of its divisors is an integer number (6875160).

Almost surely, 2^91109921 is an apocalyptic number.

It is an amenable number.

91109921 is a deficient number, since it is larger than the sum of its proper divisors (18892639).

91109921 is a wasteful number, since it uses less digits than its factorization.

91109921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2504.

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 91109921 is about 9545.1517012565. The cubic root of 91109921 is about 449.9751772316.

The spelling of 91109921 in words is "ninety-one million, one hundred nine thousand, nine hundred twenty-one".