161815543 has 4 divisors (see below), whose sum is σ = 161858880. Its totient is φ = 161772208.

The previous prime is 161815517. The next prime is 161815547. The reversal of 161815543 is 345518161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161815543 - 2¹³ = 161807351 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161815499 and 161815508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161815547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15478 + ... + 23731.

It is an arithmetic number, because the mean of its divisors is an integer number (40464720).

Almost surely, 2^161815543 is an apocalyptic number.

161815543 is a deficient number, since it is larger than the sum of its proper divisors (43337).

161815543 is an equidigital number, since it uses as much as digits as its factorization.

161815543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43336.

The product of its digits is 14400, while the sum is 34.

The square root of 161815543 is about 12720.6738422145. The cubic root of 161815543 is about 544.9291976592.

It can be divided in two parts, 1618 and 15543, that added together give a square (17161 = 131²).

The spelling of 161815543 in words is "one hundred sixty-one million, eight hundred fifteen thousand, five hundred forty-three".