161824561 has 4 divisors (see below), whose sum is σ = 163309300. Its totient is φ = 160339824.

The previous prime is 161824541. The next prime is 161824567. The reversal of 161824561 is 165428161.

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

It can be written as a sum of positive squares in 2 ways, for example, as 38192400 + 123632161 = 6180^2 + 11119^2 .

It is a cyclic number.

It is not a de Polignac number, because 161824561 - 2⁹ = 161824049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161824567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 742206 + ... + 742423.

It is an arithmetic number, because the mean of its divisors is an integer number (40827325).

Almost surely, 2^161824561 is an apocalyptic number.

It is an amenable number.

161824561 is a deficient number, since it is larger than the sum of its proper divisors (1484739).

161824561 is a wasteful number, since it uses less digits than its factorization.

161824561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1484738.

The product of its digits is 11520, while the sum is 34.

The square root of 161824561 is about 12721.0282996305. The cubic root of 161824561 is about 544.9393204614.

The spelling of 161824561 in words is "one hundred sixty-one million, eight hundred twenty-four thousand, five hundred sixty-one".