209868155117 has 4 divisors (see below), whose sum is σ = 209871004860. Its totient is φ = 209865305376.

The previous prime is 209868155093. The next prime is 209868155141. The reversal of 209868155117 is 711551868902.

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 (209868155093) and next prime (209868155141).

It can be written as a sum of positive squares in 2 ways, for example, as 103387328521 + 106480826596 = 321539^2 + 326314^2 .

It is a cyclic number.

It is not a de Polignac number, because 209868155117 - 2⁶ = 209868155053 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 (209868155317) 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, 1311392 + ... + 1462697.

It is an arithmetic number, because the mean of its divisors is an integer number (52467751215).

Almost surely, 2^209868155117 is an apocalyptic number.

It is an amenable number.

209868155117 is a deficient number, since it is larger than the sum of its proper divisors (2849743).

209868155117 is an equidigital number, since it uses as much as digits as its factorization.

209868155117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2849742.

The product of its (nonzero) digits is 1209600, while the sum is 53.

The spelling of 209868155117 in words is "two hundred nine billion, eight hundred sixty-eight million, one hundred fifty-five thousand, one hundred seventeen".