217686157 has 8 divisors (see below), whose sum is σ = 235064984. Its totient is φ = 200397888.

The previous prime is 217686137. The next prime is 217686163. The reversal of 217686157 is 751686712.

217686157 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 11792356 + 205893801 = 3434^2 + 14349^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217686157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217686107) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17598 + ... + 27295.

It is an arithmetic number, because the mean of its divisors is an integer number (29383123).

Almost surely, 2^217686157 is an apocalyptic number.

It is an amenable number.

217686157 is a deficient number, since it is larger than the sum of its proper divisors (17378827).

217686157 is a wasteful number, since it uses less digits than its factorization.

217686157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45279.

The product of its digits is 141120, while the sum is 43.

The square root of 217686157 is about 14754.1911672582. The cubic root of 217686157 is about 601.5572114725.

The spelling of 217686157 in words is "two hundred seventeen million, six hundred eighty-six thousand, one hundred fifty-seven".