218487978667 has 4 divisors (see below), whose sum is σ = 249700547056. Its totient is φ = 187275410280.

The previous prime is 218487978607. The next prime is 218487978673. The reversal of 218487978667 is 766879784812.

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

It is not a de Polignac number, because 218487978667 - 2²³ = 218479590059 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 218487978667.

It is not an unprimeable number, because it can be changed into a prime (218487978607) 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, 15606284184 + ... + 15606284197.

It is an arithmetic number, because the mean of its divisors is an integer number (62425136764).

Almost surely, 2^218487978667 is an apocalyptic number.

218487978667 is a deficient number, since it is larger than the sum of its proper divisors (31212568389).

218487978667 is an equidigital number, since it uses as much as digits as its factorization.

218487978667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31212568388.

The product of its digits is 455196672, while the sum is 73.

The spelling of 218487978667 in words is "two hundred eighteen billion, four hundred eighty-seven million, nine hundred seventy-eight thousand, six hundred sixty-seven".