2100105991 has 2 divisors, whose sum is σ = 2100105992. Its totient is φ = 2100105990.

The previous prime is 2100105989. The next prime is 2100106007. The reversal of 2100105991 is 1995010012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2100105991 - 2¹ = 2100105989 is a prime.

Together with 2100105989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2100105941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050052995 + 1050052996.

It is an arithmetic number, because the mean of its divisors is an integer number (1050052996).

Almost surely, 2^2100105991 is an apocalyptic number.

2100105991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2100105991 is an equidigital number, since it uses as much as digits as its factorization.

2100105991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 810, while the sum is 28.

The square root of 2100105991 is about 45826.9133915868. The cubic root of 2100105991 is about 1280.6007090483.

The spelling of 2100105991 in words is "two billion, one hundred million, one hundred five thousand, nine hundred ninety-one".