217157715428 has 72 divisors (see below), whose sum is σ = 405352415160. Its totient is φ = 101692177920.

The previous prime is 217157715421. The next prime is 217157715451. The reversal of 217157715428 is 824517751712.

It can be written as a sum of positive squares in 4 ways, for example, as 40857664 + 217116857764 = 6392^2 + 465958^2 .

It is not an unprimeable number, because it can be changed into a prime (217157715421) 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, 19937408 + ... + 19948296.

It is an arithmetic number, because the mean of its divisors is an integer number (5629894655).

Almost surely, 2^217157715428 is an apocalyptic number.

It is an amenable number.

217157715428 is a deficient number, since it is larger than the sum of its proper divisors (188194699732).

217157715428 is a wasteful number, since it uses less digits than its factorization.

217157715428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11085 (or 11036 counting only the distinct ones).

The product of its digits is 1097600, while the sum is 50.

The spelling of 217157715428 in words is "two hundred seventeen billion, one hundred fifty-seven million, seven hundred fifteen thousand, four hundred twenty-eight".