91388813 has 4 divisors (see below), whose sum is σ = 91440768. Its totient is φ = 91336860.

The previous prime is 91388783. The next prime is 91388827. The reversal of 91388813 is 31888319.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31888319 = 1303 ⋅24473.

It is a cyclic number.

It is not a de Polignac number, because 91388813 - 2¹⁰ = 91387789 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91388833) 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, 23243 + ... + 26888.

It is an arithmetic number, because the mean of its divisors is an integer number (22860192).

Almost surely, 2^91388813 is an apocalyptic number.

It is an amenable number.

91388813 is a deficient number, since it is larger than the sum of its proper divisors (51955).

91388813 is a wasteful number, since it uses less digits than its factorization.

91388813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51954.

The product of its digits is 41472, while the sum is 41.

The square root of 91388813 is about 9559.7496306127. The cubic root of 91388813 is about 450.4338416843.

The spelling of 91388813 in words is "ninety-one million, three hundred eighty-eight thousand, eight hundred thirteen".