209727840109 has 4 divisors (see below), whose sum is σ = 210484980604. Its totient is φ = 208970699616.

The previous prime is 209727840097. The next prime is 209727840121. The reversal of 209727840109 is 901048727902.

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

It is an interprime number because it is at equal distance from previous prime (209727840097) and next prime (209727840121).

It can be written as a sum of positive squares in 2 ways, for example, as 23554575625 + 186173264484 = 153475^2 + 431478^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209727840109 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 (209727849109) 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, 378569832 + ... + 378570385.

It is an arithmetic number, because the mean of its divisors is an integer number (52621245151).

Almost surely, 2^209727840109 is an apocalyptic number.

It is an amenable number.

209727840109 is a deficient number, since it is larger than the sum of its proper divisors (757140495).

209727840109 is an equidigital number, since it uses as much as digits as its factorization.

209727840109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 757140494.

The product of its (nonzero) digits is 508032, while the sum is 49.

The spelling of 209727840109 in words is "two hundred nine billion, seven hundred twenty-seven million, eight hundred forty thousand, one hundred nine".