217471657957 has 4 divisors (see below), whose sum is σ = 217484397900. Its totient is φ = 217458918016.

The previous prime is 217471657951. The next prime is 217471657969. The reversal of 217471657957 is 759756174712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 140894378881 + 76577279076 = 375359^2 + 276726^2 .

It is a cyclic number.

It is not a de Polignac number, because 217471657957 - 2¹⁹ = 217471133669 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 217471657895 and 217471657904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217471657951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6344332 + ... + 6378517.

It is an arithmetic number, because the mean of its divisors is an integer number (54371099475).

Almost surely, 2^217471657957 is an apocalyptic number.

It is an amenable number.

217471657957 is a deficient number, since it is larger than the sum of its proper divisors (12739943).

217471657957 is a wasteful number, since it uses less digits than its factorization.

217471657957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12739942.

The product of its digits is 25930800, while the sum is 61.

The spelling of 217471657957 in words is "two hundred seventeen billion, four hundred seventy-one million, six hundred fifty-seven thousand, nine hundred fifty-seven".