217728953 has 6 divisors (see below), whose sum is σ = 235765854. Its totient is φ = 200980416.

The previous prime is 217728913. The next prime is 217729019. The reversal of 217728953 is 359827712.

It can be written as a sum of positive squares in 3 ways, for example, as 5968249 + 211760704 = 2443^2 + 14552^2 .

It is not a de Polignac number, because 217728953 - 2¹⁶ = 217663417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217728913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 644000 + ... + 644337.

It is an arithmetic number, because the mean of its divisors is an integer number (39294309).

Almost surely, 2^217728953 is an apocalyptic number.

It is an amenable number.

217728953 is a deficient number, since it is larger than the sum of its proper divisors (18036901).

217728953 is a wasteful number, since it uses less digits than its factorization.

217728953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1288363 (or 1288350 counting only the distinct ones).

The product of its digits is 211680, while the sum is 44.

The square root of 217728953 is about 14755.6413957510. The cubic root of 217728953 is about 601.5966299269.

The spelling of 217728953 in words is "two hundred seventeen million, seven hundred twenty-eight thousand, nine hundred fifty-three".