161665543 has 8 divisors (see below), whose sum is σ = 178807328. Its totient is φ = 145196064.

The previous prime is 161665531. The next prime is 161665561. The reversal of 161665543 is 345566161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161665543 - 2²⁵ = 128111111 is a prime.

It is a super-2 number, since 2×161665543² = 52271495586969698, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161665513) 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, 167571 + ... + 168532.

It is an arithmetic number, because the mean of its divisors is an integer number (22350916).

Almost surely, 2^161665543 is an apocalyptic number.

161665543 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

161665543 is a deficient number, since it is larger than the sum of its proper divisors (17141785).

161665543 is a wasteful number, since it uses less digits than its factorization.

161665543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336153.

The product of its digits is 64800, while the sum is 37.

The square root of 161665543 is about 12714.7765611512. The cubic root of 161665543 is about 544.7607658590.

The spelling of 161665543 in words is "one hundred sixty-one million, six hundred sixty-five thousand, five hundred forty-three".