217957213880 has 128 divisors (see below), whose sum is σ = 570614906880. Its totient is φ = 73378552320.

The previous prime is 217957213861. The next prime is 217957213883. The reversal of 217957213880 is 88312759712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217957213883) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10357049 + ... + 10378071.

It is an arithmetic number, because the mean of its divisors is an integer number (4457928960).

Almost surely, 2^217957213880 is an apocalyptic number.

217957213880 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 217957213880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (285307453440).

217957213880 is an abundant number, since it is smaller than the sum of its proper divisors (352657693000).

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

217957213880 is a wasteful number, since it uses less digits than its factorization.

217957213880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21709 (or 21705 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 53.

The spelling of 217957213880 in words is "two hundred seventeen billion, nine hundred fifty-seven million, two hundred thirteen thousand, eight hundred eighty".