161665563 has 16 divisors (see below), whose sum is σ = 230804640. Its totient is φ = 100294656.

The previous prime is 161665561. The next prime is 161665579. The reversal of 161665563 is 365566161.

It is not a de Polignac number, because 161665563 - 2¹ = 161665561 is a prime.

It is a super-2 number, since 2×161665563² = 52271508520213938, which contains 22 as substring.

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 (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13270 + ... + 22347.

It is an arithmetic number, because the mean of its divisors is an integer number (14425290).

Almost surely, 2^161665563 is an apocalyptic number.

161665563 is a deficient number, since it is larger than the sum of its proper divisors (69139077).

161665563 is a wasteful number, since it uses less digits than its factorization.

161665563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35726.

The product of its digits is 97200, while the sum is 39.

The square root of 161665563 is about 12714.7773476377. Note that the first 3 decimals coincide. The cubic root of 161665563 is about 544.7607883235.

The spelling of 161665563 in words is "one hundred sixty-one million, six hundred sixty-five thousand, five hundred sixty-three".