217978255 has 8 divisors (see below), whose sum is σ = 285353424. Its totient is φ = 158529600.

The previous prime is 217978249. The next prime is 217978261. The reversal of 217978255 is 552879712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (217978249) and next prime (217978261).

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

It is not a de Polignac number, because 217978255 - 2³ = 217978247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1981566 + ... + 1981675.

It is an arithmetic number, because the mean of its divisors is an integer number (35669178).

Almost surely, 2^217978255 is an apocalyptic number.

217978255 is a deficient number, since it is larger than the sum of its proper divisors (67375169).

217978255 is a wasteful number, since it uses less digits than its factorization.

217978255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3963257.

The product of its digits is 352800, while the sum is 46.

The square root of 217978255 is about 14764.0866632515. The cubic root of 217978255 is about 601.8261538904.

The spelling of 217978255 in words is "two hundred seventeen million, nine hundred seventy-eight thousand, two hundred fifty-five".