165797797561 has 32 divisors (see below), whose sum is σ = 187102089216. Its totient is φ = 145611216000.

The previous prime is 165797797553. The next prime is 165797797573.

165797797561 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 165797797561 - 2³ = 165797797553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165797797661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20406846 + ... + 20414968.

It is an arithmetic number, because the mean of its divisors is an integer number (5846940288).

Almost surely, 2^165797797561 is an apocalyptic number.

165797797561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165797797561 is a deficient number, since it is larger than the sum of its proper divisors (21304291655).

165797797561 is a wasteful number, since it uses less digits than its factorization.

165797797561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8613.

The product of its digits is 175032900, while the sum is 70.

The spelling of 165797797561 in words is "one hundred sixty-five billion, seven hundred ninety-seven million, seven hundred ninety-seven thousand, five hundred sixty-one".