217661138240 has 224 divisors, whose sum is σ = 658495186944. Its totient is φ = 66663751680.

The previous prime is 217661138221. The next prime is 217661138257. The reversal of 217661138240 is 42831166712.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 782162 + ... + 1023278.

It is an arithmetic number, because the mean of its divisors is an integer number (2939710656).

Almost surely, 2^217661138240 is an apocalyptic number.

217661138240 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 217661138240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (329247593472).

217661138240 is an abundant number, since it is smaller than the sum of its proper divisors (440834048704).

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

217661138240 is a wasteful number, since it uses less digits than its factorization.

217661138240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241185 (or 241175 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 41.

The spelling of 217661138240 in words is "two hundred seventeen billion, six hundred sixty-one million, one hundred thirty-eight thousand, two hundred forty".