165557776661 has 4 divisors (see below), whose sum is σ = 167653444800. Its totient is φ = 163462108524.

The previous prime is 165557776639. The next prime is 165557776717. The reversal of 165557776661 is 166677755561.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165557776661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 165557776594 and 165557776603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165557779661) 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, 1047833951 + ... + 1047834108.

It is an arithmetic number, because the mean of its divisors is an integer number (41913361200).

Almost surely, 2^165557776661 is an apocalyptic number.

It is an amenable number.

165557776661 is a deficient number, since it is larger than the sum of its proper divisors (2095668139).

165557776661 is an equidigital number, since it uses as much as digits as its factorization.

165557776661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2095668138.

The product of its digits is 55566000, while the sum is 62.

The spelling of 165557776661 in words is "one hundred sixty-five billion, five hundred fifty-seven million, seven hundred seventy-six thousand, six hundred sixty-one".