91491569 has 16 divisors (see below), whose sum is σ = 104972112. Its totient is φ = 78993408.

The previous prime is 91491529. The next prime is 91491577. The reversal of 91491569 is 96519419.

It can be written as a sum of positive squares in 8 ways, for example, as 1488400 + 90003169 = 1220^2 + 9487^2 .

It is not a de Polignac number, because 91491569 - 2¹⁶ = 91426033 is a prime.

It is a super-4 number, since 4×91491569⁴ (a number of 33 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91491529) 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, 37037 + ... + 39429.

It is an arithmetic number, because the mean of its divisors is an integer number (6560757).

Almost surely, 2^91491569 is an apocalyptic number.

It is an amenable number.

91491569 is a deficient number, since it is larger than the sum of its proper divisors (13480543).

91491569 is a wasteful number, since it uses less digits than its factorization.

91491569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2596.

The product of its digits is 87480, while the sum is 44.

The square root of 91491569 is about 9565.1225292727. The cubic root of 91491569 is about 450.6025984569.

The spelling of 91491569 in words is "ninety-one million, four hundred ninety-one thousand, five hundred sixty-nine".