217908253478 has 4 divisors (see below), whose sum is σ = 326862380220. Its totient is φ = 108954126738.

The previous prime is 217908253471. The next prime is 217908253481. The reversal of 217908253478 is 874352809712.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217908253471) 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 as a sum of consecutive naturals, namely, 54477063368 + ... + 54477063371.

It is an arithmetic number, because the mean of its divisors is an integer number (81715595055).

Almost surely, 2^217908253478 is an apocalyptic number.

217908253478 is a deficient number, since it is larger than the sum of its proper divisors (108954126742).

217908253478 is a wasteful number, since it uses less digits than its factorization.

217908253478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108954126741.

The product of its (nonzero) digits is 6773760, while the sum is 56.

The spelling of 217908253478 in words is "two hundred seventeen billion, nine hundred eight million, two hundred fifty-three thousand, four hundred seventy-eight".