218539038721 has 4 divisors (see below), whose sum is σ = 218544061744. Its totient is φ = 218534015700.

The previous prime is 218539038703. The next prime is 218539038743. The reversal of 218539038721 is 127830935812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 218539038721 - 2²³ = 218530650113 is a prime.

It is a super-2 number, since 2×218539038721² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218539035721) 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, 2445675 + ... + 2533456.

It is an arithmetic number, because the mean of its divisors is an integer number (54636015436).

Almost surely, 2^218539038721 is an apocalyptic number.

It is an amenable number.

218539038721 is a deficient number, since it is larger than the sum of its proper divisors (5023023).

218539038721 is an equidigital number, since it uses as much as digits as its factorization.

218539038721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5023022.

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 218539038721 in words is "two hundred eighteen billion, five hundred thirty-nine million, thirty-eight thousand, seven hundred twenty-one".