1891110197 has 2 divisors, whose sum is σ = 1891110198. Its totient is φ = 1891110196.

The previous prime is 1891110173. The next prime is 1891110217. The reversal of 1891110197 is 7910111981.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1281711601 + 609398596 = 35801^2 + 24686^2 .

It is a cyclic number.

It is not a de Polignac number, because 1891110197 - 2¹⁰ = 1891109173 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1891110197.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1891116197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 945555098 + 945555099.

It is an arithmetic number, because the mean of its divisors is an integer number (945555099).

Almost surely, 2^1891110197 is an apocalyptic number.

It is an amenable number.

1891110197 is a deficient number, since it is larger than the sum of its proper divisors (1).

1891110197 is an equidigital number, since it uses as much as digits as its factorization.

1891110197 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 38.

The square root of 1891110197 is about 43486.8968426123. The cubic root of 1891110197 is about 1236.6276292541.

The spelling of 1891110197 in words is "one billion, eight hundred ninety-one million, one hundred ten thousand, one hundred ninety-seven".