161665516505 has 16 divisors (see below), whose sum is σ = 216221374080. Its totient is φ = 115318063872.

The previous prime is 161665516501. The next prime is 161665516511. The reversal of 161665516505 is 505615566161.

It is a cyclic number.

It is not a de Polignac number, because 161665516505 - 2² = 161665516501 is a prime.

It is a super-2 number, since 2×161665516505² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161665516505.

It is not an unprimeable number, because it can be changed into a prime (161665516501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50049629 + ... + 50052858.

It is an arithmetic number, because the mean of its divisors is an integer number (13513835880).

Almost surely, 2^161665516505 is an apocalyptic number.

It is an amenable number.

161665516505 is a deficient number, since it is larger than the sum of its proper divisors (54555857575).

161665516505 is a wasteful number, since it uses less digits than its factorization.

161665516505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100102528.

The product of its (nonzero) digits is 810000, while the sum is 47.

The spelling of 161665516505 in words is "one hundred sixty-one billion, six hundred sixty-five million, five hundred sixteen thousand, five hundred five".