217878479710864 has 120 divisors (see below), whose sum is σ = 500314015641528. Its totient is φ = 91629857249280.

The previous prime is 217878479710777. The next prime is 217878479710883. The reversal of 217878479710864 is 468017974878712.

It can be written as a sum of positive squares in 4 ways, for example, as 171025714182400 + 46852765528464 = 13077680^2 + 6844908^2 .

It is a super-2 number, since 2×217878479710864² (a number of 29 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1612434 + ... + 20936974.

Almost surely, 2^{217878479710864} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217878479710864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (250157007820764).

217878479710864 is an abundant number, since it is smaller than the sum of its proper divisors (282435535930664).

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

217878479710864 is a wasteful number, since it uses less digits than its factorization.

217878479710864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19324833 (or 19324820 counting only the distinct ones).

The product of its (nonzero) digits is 2124251136, while the sum is 79.

The spelling of 217878479710864 in words is "two hundred seventeen trillion, eight hundred seventy-eight billion, four hundred seventy-nine million, seven hundred ten thousand, eight hundred sixty-four".