217686265720 has 256 divisors, whose sum is σ = 651610137600. Its totient is φ = 63397416960.

The previous prime is 217686265679. The next prime is 217686265747. The reversal of 217686265720 is 27562686712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4246482 + ... + 4297438.

It is an arithmetic number, because the mean of its divisors is an integer number (2545352100).

Almost surely, 2^217686265720 is an apocalyptic number.

217686265720 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 217686265720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (325805068800).

217686265720 is an abundant number, since it is smaller than the sum of its proper divisors (433923871880).

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

217686265720 is a wasteful number, since it uses less digits than its factorization.

217686265720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51078 (or 51074 counting only the distinct ones).

The product of its (nonzero) digits is 3386880, while the sum is 52.

The spelling of 217686265720 in words is "two hundred seventeen billion, six hundred eighty-six million, two hundred sixty-five thousand, seven hundred twenty".