91643641205 has 4 divisors (see below), whose sum is σ = 109972369452. Its totient is φ = 73314912960.

The previous prime is 91643641163. The next prime is 91643641207. The reversal of 91643641205 is 50214634619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50214634619 = 37 ⋅1357152287.

It can be written as a sum of positive squares in 2 ways, for example, as 46784824804 + 44858816401 = 216298^2 + 211799^2 .

It is a de Polignac number, because none of the positive numbers 2^k-91643641205 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 (91643641207) 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, 9164364116 + ... + 9164364125.

It is an arithmetic number, because the mean of its divisors is an integer number (27493092363).

Almost surely, 2^91643641205 is an apocalyptic number.

It is an amenable number.

91643641205 is a deficient number, since it is larger than the sum of its proper divisors (18328728247).

91643641205 is a wasteful number, since it uses less digits than its factorization.

91643641205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18328728246.

The product of its (nonzero) digits is 155520, while the sum is 41.

The spelling of 91643641205 in words is "ninety-one billion, six hundred forty-three million, six hundred forty-one thousand, two hundred five".