2109391997 has 4 divisors (see below), whose sum is σ = 2149191900. Its totient is φ = 2069592096.

The previous prime is 2109391987. The next prime is 2109392009. The reversal of 2109391997 is 7991939012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1642356676 + 467035321 = 40526^2 + 21611^2 .

It is a cyclic number.

It is not a de Polignac number, because 2109391997 - 2²⁰ = 2108343421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2109391987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19899872 + ... + 19899977.

It is an arithmetic number, because the mean of its divisors is an integer number (537297975).

Almost surely, 2^2109391997 is an apocalyptic number.

It is an amenable number.

2109391997 is a deficient number, since it is larger than the sum of its proper divisors (39799903).

2109391997 is an equidigital number, since it uses as much as digits as its factorization.

2109391997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39799902.

The product of its (nonzero) digits is 275562, while the sum is 50.

The square root of 2109391997 is about 45928.1177167103. The cubic root of 2109391997 is about 1282.4854046751.

The spelling of 2109391997 in words is "two billion, one hundred nine million, three hundred ninety-one thousand, nine hundred ninety-seven".