217868931 has 12 divisors (see below), whose sum is σ = 359656752. Its totient is φ = 124496496.

The previous prime is 217868929. The next prime is 217868933. The reversal of 217868931 is 139868712.

It is an interprime number because it is at equal distance from previous prime (217868929) and next prime (217868933).

It is not a de Polignac number, because 217868931 - 2¹ = 217868929 is a prime.

It is a super-2 number, since 2×217868931² = 94933742190165522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (217868933) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1729056 + ... + 1729181.

It is an arithmetic number, because the mean of its divisors is an integer number (29971396).

Almost surely, 2^217868931 is an apocalyptic number.

217868931 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

217868931 is a deficient number, since it is larger than the sum of its proper divisors (141787821).

217868931 is a wasteful number, since it uses less digits than its factorization.

217868931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3458250 (or 3458247 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 217868931 is about 14760.3838364725. The cubic root of 217868931 is about 601.7255245182.

The spelling of 217868931 in words is "two hundred seventeen million, eight hundred sixty-eight thousand, nine hundred thirty-one".