218639086542509 has 4 divisors (see below), whose sum is σ = 222223333862940. Its totient is φ = 215054839222080.

The previous prime is 218639086542467. The next prime is 218639086542511. The reversal of 218639086542509 is 905245680936812.

It is a happy number.

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 32163757116100 + 186475329426409 = 5671310^2 + 13655597^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218639086542509 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 (218639086542109) 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, 1792123660124 + ... + 1792123660245.

It is an arithmetic number, because the mean of its divisors is an integer number (55555833465735).

Almost surely, 2^{218639086542509} is an apocalyptic number.

It is an amenable number.

218639086542509 is a deficient number, since it is larger than the sum of its proper divisors (3584247320431).

218639086542509 is an equidigital number, since it uses as much as digits as its factorization.

218639086542509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3584247320430.

The product of its (nonzero) digits is 223948800, while the sum is 68.

The spelling of 218639086542509 in words is "two hundred eighteen trillion, six hundred thirty-nine billion, eighty-six million, five hundred forty-two thousand, five hundred nine".