1991106101 has 2 divisors, whose sum is σ = 1991106102. Its totient is φ = 1991106100.

The previous prime is 1991106071. The next prime is 1991106119. The reversal of 1991106101 is 1016011991.

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., 1924927876 + 66178225 = 43874^2 + 8135^2 .

It is an emirp because it is prime and its reverse (1016011991) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1019011661 and 1661109101.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1991106101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991106151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995553050 + 995553051.

It is an arithmetic number, because the mean of its divisors is an integer number (995553051).

Almost surely, 2^1991106101 is an apocalyptic number.

It is an amenable number.

1991106101 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991106101 is an equidigital number, since it uses as much as digits as its factorization.

1991106101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 486, while the sum is 29.

The square root of 1991106101 is about 44621.8119421433. The cubic root of 1991106101 is about 1258.0506728973.

The spelling of 1991106101 in words is "one billion, nine hundred ninety-one million, one hundred six thousand, one hundred one".