218532971987 has 4 divisors (see below), whose sum is σ = 238399605816. Its totient is φ = 198666338160.

The previous prime is 218532971981. The next prime is 218532972037. The reversal of 218532971987 is 789179235812.

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

It is a cyclic number.

It is not a de Polignac number, because 218532971987 - 2⁴ = 218532971971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218532971981) 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, 9933316898 + ... + 9933316919.

It is an arithmetic number, because the mean of its divisors is an integer number (59599901454).

Almost surely, 2^218532971987 is an apocalyptic number.

218532971987 is a deficient number, since it is larger than the sum of its proper divisors (19866633829).

218532971987 is a wasteful number, since it uses less digits than its factorization.

218532971987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19866633828.

The product of its digits is 15240960, while the sum is 62.

The spelling of 218532971987 in words is "two hundred eighteen billion, five hundred thirty-two million, nine hundred seventy-one thousand, nine hundred eighty-seven".