2109947857 has 2 divisors, whose sum is σ = 2109947858. Its totient is φ = 2109947856.

The previous prime is 2109947821. The next prime is 2109947887. The reversal of 2109947857 is 7587499012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1365967681 + 743980176 = 36959^2 + 27276^2 .

It is a cyclic number.

It is not a de Polignac number, because 2109947857 - 2¹⁵ = 2109915089 is a prime.

It is not a weakly prime, because it can be changed into another prime (2109947887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1054973928 + 1054973929.

It is an arithmetic number, because the mean of its divisors is an integer number (1054973929).

Almost surely, 2^2109947857 is an apocalyptic number.

It is an amenable number.

2109947857 is a deficient number, since it is larger than the sum of its proper divisors (1).

2109947857 is an equidigital number, since it uses as much as digits as its factorization.

2109947857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1270080, while the sum is 52.

The square root of 2109947857 is about 45934.1687309132. The cubic root of 2109947857 is about 1282.5980468849.

The spelling of 2109947857 in words is "two billion, one hundred nine million, nine hundred forty-seven thousand, eight hundred fifty-seven".