91243813 has 4 divisors (see below), whose sum is σ = 93709900. Its totient is φ = 88777728.

The previous prime is 91243759. The next prime is 91243837. The reversal of 91243813 is 31834219.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31834219 = 1579 ⋅20161.

It can be written as a sum of positive squares in 2 ways, for example, as 78269409 + 12974404 = 8847^2 + 3602^2 .

It is a cyclic number.

It is not a de Polignac number, because 91243813 - 2²¹ = 89146661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91243513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1232988 + ... + 1233061.

It is an arithmetic number, because the mean of its divisors is an integer number (23427475).

Almost surely, 2^91243813 is an apocalyptic number.

It is an amenable number.

91243813 is a deficient number, since it is larger than the sum of its proper divisors (2466087).

91243813 is a wasteful number, since it uses less digits than its factorization.

91243813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2466086.

The product of its digits is 5184, while the sum is 31.

The square root of 91243813 is about 9552.1627394010. The cubic root of 91243813 is about 450.1954920155.

The spelling of 91243813 in words is "ninety-one million, two hundred forty-three thousand, eight hundred thirteen".