217261751121 has 20 divisors (see below), whose sum is σ = 324571670500. Its totient is φ = 144832167936.

The previous prime is 217261751071. The next prime is 217261751207. The reversal of 217261751121 is 121157162712.

It is a happy number.

217261751121 is a `hidden beast` number, since 2 + 1 + 7 + 2 + 617 + 5 + 11 + 21 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 137759745600 + 79502005521 = 371160^2 + 281961^2 .

It is not a de Polignac number, because 217261751121 - 2¹⁴ = 217261734737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217261751821) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1387665 + ... + 1536273.

It is an arithmetic number, because the mean of its divisors is an integer number (16228583525).

Almost surely, 2^217261751121 is an apocalyptic number.

It is an amenable number.

217261751121 is a deficient number, since it is larger than the sum of its proper divisors (107309919379).

217261751121 is a wasteful number, since it uses less digits than its factorization.

217261751121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166670 (or 166661 counting only the distinct ones).

The product of its digits is 11760, while the sum is 36.

The spelling of 217261751121 in words is "two hundred seventeen billion, two hundred sixty-one million, seven hundred fifty-one thousand, one hundred twenty-one".