217255861368 has 640 divisors, whose sum is σ = 800773585920. Its totient is φ = 53456578560.

The previous prime is 217255861357. The next prime is 217255861379. The reversal of 217255861368 is 863168552712.

217255861368 is a `hidden beast` number, since 2 + 1 + 7 + 25 + 586 + 1 + 36 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (217255861357) and next prime (217255861379).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 55604871 + ... + 55608777.

It is an arithmetic number, because the mean of its divisors is an integer number (1251208728).

Almost surely, 2^217255861368 is an apocalyptic number.

217255861368 is a gapful number since it is divisible by the number (28) 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 217255861368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (400386792960).

217255861368 is an abundant number, since it is smaller than the sum of its proper divisors (583517724552).

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

217255861368 is a wasteful number, since it uses less digits than its factorization.

217255861368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4009 (or 3996 counting only the distinct ones).

The product of its digits is 4838400, while the sum is 54.

The spelling of 217255861368 in words is "two hundred seventeen billion, two hundred fifty-five million, eight hundred sixty-one thousand, three hundred sixty-eight".