891491873 has 2 divisors, whose sum is σ = 891491874. Its totient is φ = 891491872.

The previous prime is 891491827. The next prime is 891491981. The reversal of 891491873 is 378194198.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 788935744 + 102556129 = 28088^2 + 10127^2 .

It is a cyclic number.

It is not a de Polignac number, because 891491873 - 2⁸ = 891491617 is a prime.

It is not a weakly prime, because it can be changed into another prime (891491773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445745936 + 445745937.

It is an arithmetic number, because the mean of its divisors is an integer number (445745937).

Almost surely, 2^891491873 is an apocalyptic number.

It is an amenable number.

891491873 is a deficient number, since it is larger than the sum of its proper divisors (1).

891491873 is an equidigital number, since it uses as much as digits as its factorization.

891491873 is an evil number, because the sum of its binary digits is even.

The product of its digits is 435456, while the sum is 50.

The square root of 891491873 is about 29857.8611591654. The cubic root of 891491873 is about 962.4373370797.

The spelling of 891491873 in words is "eight hundred ninety-one million, four hundred ninety-one thousand, eight hundred seventy-three".