217288109961 has 24 divisors (see below), whose sum is σ = 338146118856. Its totient is φ = 133659429120.

The previous prime is 217288109953. The next prime is 217288109981. The reversal of 217288109961 is 169901882712.

It is a happy number.

217288109961 is a `hidden beast` number, since 217 + 288 + 1 + 0 + 99 + 61 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 149817600 + 217138292361 = 12240^2 + 465981^2 .

It is not a de Polignac number, because 217288109961 - 2³ = 217288109953 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 217288109898 and 217288109907.

It is not an unprimeable number, because it can be changed into a prime (217288109981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 111420 + ... + 668573.

It is an arithmetic number, because the mean of its divisors is an integer number (14089421619).

Almost surely, 2^217288109961 is an apocalyptic number.

It is an amenable number.

217288109961 is a deficient number, since it is larger than the sum of its proper divisors (120858008895).

217288109961 is a wasteful number, since it uses less digits than its factorization.

217288109961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782393 (or 782390 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 54.

The spelling of 217288109961 in words is "two hundred seventeen billion, two hundred eighty-eight million, one hundred nine thousand, nine hundred sixty-one".