161665560 has 96 divisors (see below), whose sum is σ = 600481440. Its totient is φ = 36951552.

The previous prime is 161665531. The next prime is 161665561. The reversal of 161665560 is 65566161.

It is a super-2 number, since 2×161665560² = 52271506580227200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161665561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29557 + ... + 34596.

It is an arithmetic number, because the mean of its divisors is an integer number (6255015).

Almost surely, 2^161665560 is an apocalyptic number.

161665560 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161665560 is an abundant number, since it is smaller than the sum of its proper divisors (438815880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161665560 is a wasteful number, since it uses less digits than its factorization.

161665560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64177 (or 64170 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 161665560 is about 12714.7772296647. Note that the first 3 decimals coincide. The cubic root of 161665560 is about 544.7607849538.

It can be divided in two parts, 1616 and 65560, that added together give a palindrome (67176).

The spelling of 161665560 in words is "one hundred sixty-one million, six hundred sixty-five thousand, five hundred sixty".