191561873 has 2 divisors, whose sum is σ = 191561874. Its totient is φ = 191561872.

The previous prime is 191561863. The next prime is 191561879. The reversal of 191561873 is 378165191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155176849 + 36385024 = 12457^2 + 6032^2 .

It is a cyclic number.

It is not a de Polignac number, because 191561873 - 2¹⁰ = 191560849 is a prime.

It is a super-3 number, since 3×191561873³ (a number of 26 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 191561873.

It is not a weakly prime, because it can be changed into another prime (191561879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95780936 + 95780937.

It is an arithmetic number, because the mean of its divisors is an integer number (95780937).

Almost surely, 2^191561873 is an apocalyptic number.

It is an amenable number.

191561873 is a deficient number, since it is larger than the sum of its proper divisors (1).

191561873 is an equidigital number, since it uses as much as digits as its factorization.

191561873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 41.

The square root of 191561873 is about 13840.5878849130. The cubic root of 191561873 is about 576.4606824802.

The spelling of 191561873 in words is "one hundred ninety-one million, five hundred sixty-one thousand, eight hundred seventy-three".