189861817 has 4 divisors (see below), whose sum is σ = 190391040. Its totient is φ = 189332596.

The previous prime is 189861773. The next prime is 189861821. The reversal of 189861817 is 718168981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 718168981 = 251 ⋅2861231.

It is a cyclic number.

It is not a de Polignac number, because 189861817 - 2¹⁵ = 189829049 is a prime.

It is a Smith number, since the sum of its digits (49) 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 not an unprimeable number, because it can be changed into a prime (189865817) 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, 264073 + ... + 264790.

It is an arithmetic number, because the mean of its divisors is an integer number (47597760).

Almost surely, 2^189861817 is an apocalyptic number.

It is an amenable number.

189861817 is a deficient number, since it is larger than the sum of its proper divisors (529223).

189861817 is an equidigital number, since it uses as much as digits as its factorization.

189861817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529222.

The product of its digits is 193536, while the sum is 49.

The square root of 189861817 is about 13779.0354161676. The cubic root of 189861817 is about 574.7503057004.

The spelling of 189861817 in words is "one hundred eighty-nine million, eight hundred sixty-one thousand, eight hundred seventeen".