217989797718 has 96 divisors (see below), whose sum is σ = 553400563968. Its totient is φ = 56606894400.

The previous prime is 217989797699. The next prime is 217989797719. The reversal of 217989797718 is 817797989712.

It is a self number, because there is not a number n which added to its sum of digits gives 217989797718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217989797719) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24596608 + ... + 24605468.

It is an arithmetic number, because the mean of its divisors is an integer number (5764589208).

Almost surely, 2^217989797718 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217989797718, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (276700281984).

217989797718 is an abundant number, since it is smaller than the sum of its proper divisors (335410766250).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217989797718 is a wasteful number, since it uses less digits than its factorization.

217989797718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16498 (or 16491 counting only the distinct ones).

The product of its digits is 224042112, while the sum is 75.

The spelling of 217989797718 in words is "two hundred seventeen billion, nine hundred eighty-nine million, seven hundred ninety-seven thousand, seven hundred eighteen".