91388161 has 4 divisors (see below), whose sum is σ = 91431252. Its totient is φ = 91345072.

The previous prime is 91388123. The next prime is 91388183. The reversal of 91388161 is 16188319.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16188319 = 7 ⋅2312617.

It can be written as a sum of positive squares in 2 ways, for example, as 84916225 + 6471936 = 9215^2 + 2544^2 .

It is a cyclic number.

It is not a de Polignac number, because 91388161 - 2¹³ = 91379969 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 91388161.

It is not an unprimeable number, because it can be changed into a prime (91383161) 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, 18190 + ... + 22663.

It is an arithmetic number, because the mean of its divisors is an integer number (22857813).

Almost surely, 2^91388161 is an apocalyptic number.

It is an amenable number.

91388161 is a deficient number, since it is larger than the sum of its proper divisors (43091).

91388161 is a wasteful number, since it uses less digits than its factorization.

91388161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43090.

The product of its digits is 10368, while the sum is 37.

The square root of 91388161 is about 9559.7155292404. The cubic root of 91388161 is about 450.4327704972.

The spelling of 91388161 in words is "ninety-one million, three hundred eighty-eight thousand, one hundred sixty-one".