91638188893 has 4 divisors (see below), whose sum is σ = 91657803708. Its totient is φ = 91618574080.

The previous prime is 91638188801. The next prime is 91638188911. The reversal of 91638188893 is 39888183619.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 87830435044 + 3807753849 = 296362^2 + 61707^2 .

It is a cyclic number.

It is not a de Polignac number, because 91638188893 - 2²¹ = 91636091741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91638182893) 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, 9800398 + ... + 9809743.

It is an arithmetic number, because the mean of its divisors is an integer number (22914450927).

Almost surely, 2^91638188893 is an apocalyptic number.

It is an amenable number.

91638188893 is a deficient number, since it is larger than the sum of its proper divisors (19614815).

91638188893 is a wasteful number, since it uses less digits than its factorization.

91638188893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19614814.

The product of its digits is 17915904, while the sum is 64.

The spelling of 91638188893 in words is "ninety-one billion, six hundred thirty-eight million, one hundred eighty-eight thousand, eight hundred ninety-three".