217968660 has 216 divisors, whose sum is σ = 828716616. Its totient is φ = 45964800.

The previous prime is 217968649. The next prime is 217968661. The reversal of 217968660 is 66869712.

It can be written as a sum of positive squares in 4 ways, for example, as 3111696 + 214856964 = 1764^2 + 14658^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217968661) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 113710 + ... + 115610.

It is an arithmetic number, because the mean of its divisors is an integer number (3836651).

Almost surely, 2^217968660 is an apocalyptic number.

217968660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217968660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (414358308).

217968660 is an abundant number, since it is smaller than the sum of its proper divisors (610747956).

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

217968660 is a wasteful number, since it uses less digits than its factorization.

217968660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1943 (or 1931 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 217968660 is about 14763.7617157688. The cubic root of 217968660 is about 601.8173233357.

The spelling of 217968660 in words is "two hundred seventeen million, nine hundred sixty-eight thousand, six hundred sixty".