161665555618 has 16 divisors (see below), whose sum is σ = 277257602304. Its totient is φ = 69256075680.

The previous prime is 161665555559. The next prime is 161665555619. The reversal of 161665555618 is 816555566161.

It is a super-2 number, since 2×161665555618² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161665555619) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2395738 + ... + 2462293.

It is an arithmetic number, because the mean of its divisors is an integer number (17328600144).

Almost surely, 2^161665555618 is an apocalyptic number.

161665555618 is a deficient number, since it is larger than the sum of its proper divisors (115592046686).

161665555618 is a wasteful number, since it uses less digits than its factorization.

161665555618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4860417.

The product of its digits is 6480000, while the sum is 55.

The spelling of 161665555618 in words is "one hundred sixty-one billion, six hundred sixty-five million, five hundred fifty-five thousand, six hundred eighteen".