161808851 has 4 divisors (see below), whose sum is σ = 162174552. Its totient is φ = 161443152.

The previous prime is 161808833. The next prime is 161808859. The reversal of 161808851 is 158808161.

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 161808851 - 2¹⁰ = 161807827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161808859) 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, 182186 + ... + 183071.

It is an arithmetic number, because the mean of its divisors is an integer number (40543638).

Almost surely, 2^161808851 is an apocalyptic number.

161808851 is a deficient number, since it is larger than the sum of its proper divisors (365701).

161808851 is an equidigital number, since it uses as much as digits as its factorization.

161808851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365700.

The product of its (nonzero) digits is 15360, while the sum is 38.

The square root of 161808851 is about 12720.4108031148. The cubic root of 161808851 is about 544.9216855739.

The spelling of 161808851 in words is "one hundred sixty-one million, eight hundred eight thousand, eight hundred fifty-one".