161819815 has 4 divisors (see below), whose sum is σ = 194183784. Its totient is φ = 129455848.

The previous prime is 161819803. The next prime is 161819837. The reversal of 161819815 is 518918161.

161819815 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 161819815 - 2²¹ = 159722663 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16181977 + ... + 16181986.

It is an arithmetic number, because the mean of its divisors is an integer number (48545946).

Almost surely, 2^161819815 is an apocalyptic number.

161819815 is a deficient number, since it is larger than the sum of its proper divisors (32363969).

161819815 is an equidigital number, since it uses as much as digits as its factorization.

161819815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32363968.

The product of its digits is 17280, while the sum is 40.

The square root of 161819815 is about 12720.8417567392. The cubic root of 161819815 is about 544.9339930721.

The spelling of 161819815 in words is "one hundred sixty-one million, eight hundred nineteen thousand, eight hundred fifteen".