165657756561 has 32 divisors (see below), whose sum is σ = 242217862656. Its totient is φ = 99873648000.

The previous prime is 165657756553. The next prime is 165657756571.

165657756561 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 165657756561 - 2³ = 165657756553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 165657756495 and 165657756504.

It is not an unprimeable number, because it can be changed into a prime (165657756571) 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, 18217626 + ... + 18226716.

It is an arithmetic number, because the mean of its divisors is an integer number (7569308208).

Almost surely, 2^165657756561 is an apocalyptic number.

165657756561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165657756561 is a deficient number, since it is larger than the sum of its proper divisors (76560106095).

165657756561 is a wasteful number, since it uses less digits than its factorization.

165657756561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11933.

The product of its digits is 39690000, while the sum is 60.

The spelling of 165657756561 in words is "one hundred sixty-five billion, six hundred fifty-seven million, seven hundred fifty-six thousand, five hundred sixty-one".