209106986991 has 16 divisors (see below), whose sum is σ = 318705907200. Its totient is φ = 119464698528.

The previous prime is 209106986981. The next prime is 209106986999. The reversal of 209106986991 is 199689601902.

It is not a de Polignac number, because 209106986991 - 2¹⁵ = 209106954223 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209106986999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 939051 + ... + 1140188.

It is an arithmetic number, because the mean of its divisors is an integer number (19919119200).

Almost surely, 2^209106986991 is an apocalyptic number.

209106986991 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

209106986991 is a deficient number, since it is larger than the sum of its proper divisors (109598920209).

209106986991 is a wasteful number, since it uses less digits than its factorization.

209106986991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2084038.

The product of its (nonzero) digits is 3779136, while the sum is 60.

The spelling of 209106986991 in words is "two hundred nine billion, one hundred six million, nine hundred eighty-six thousand, nine hundred ninety-one".