191816993 has 4 divisors (see below), whose sum is σ = 192000900. Its totient is φ = 191633088.

The previous prime is 191816971. The next prime is 191817007. The reversal of 191816993 is 399618191.

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 164275489 + 27541504 = 12817^2 + 5248^2 .

It is a cyclic number.

It is not a de Polignac number, because 191816993 - 2¹⁶ = 191751457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191816903) 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, 90380 + ... + 92477.

It is an arithmetic number, because the mean of its divisors is an integer number (48000225).

Almost surely, 2^191816993 is an apocalyptic number.

It is an amenable number.

191816993 is a deficient number, since it is larger than the sum of its proper divisors (183907).

191816993 is a wasteful number, since it uses less digits than its factorization.

191816993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183906.

The product of its digits is 104976, while the sum is 47.

The square root of 191816993 is about 13849.8011899088. The cubic root of 191816993 is about 576.7164769624.

The spelling of 191816993 in words is "one hundred ninety-one million, eight hundred sixteen thousand, nine hundred ninety-three".