65557320191 has 4 divisors (see below), whose sum is σ = 71517076584. Its totient is φ = 59597563800.

The previous prime is 65557320161. The next prime is 65557320209. The reversal of 65557320191 is 19102375556.

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

It is a cyclic number.

It is not a de Polignac number, because 65557320191 - 2²² = 65553125887 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 (65557320161) 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, 2979878180 + ... + 2979878201.

It is an arithmetic number, because the mean of its divisors is an integer number (17879269146).

Almost surely, 2^65557320191 is an apocalyptic number.

65557320191 is a deficient number, since it is larger than the sum of its proper divisors (5959756393).

65557320191 is a wasteful number, since it uses less digits than its factorization.

65557320191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5959756392.

The product of its (nonzero) digits is 283500, while the sum is 44.

The spelling of 65557320191 in words is "sixty-five billion, five hundred fifty-seven million, three hundred twenty thousand, one hundred ninety-one".