217931138 has 16 divisors (see below), whose sum is σ = 338743680. Its totient is φ = 105080976.

The previous prime is 217931137. The next prime is 217931149. The reversal of 217931138 is 831139712.

It is a happy number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 217931098 and 217931107.

It is not an unprimeable number, because it can be changed into a prime (217931137) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9245 + ... + 22832.

It is an arithmetic number, because the mean of its divisors is an integer number (21171480).

Almost surely, 2^217931138 is an apocalyptic number.

217931138 is a deficient number, since it is larger than the sum of its proper divisors (120812542).

217931138 is a wasteful number, since it uses less digits than its factorization.

217931138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32201.

The product of its digits is 9072, while the sum is 35.

The square root of 217931138 is about 14762.4909144765. The cubic root of 217931138 is about 601.7827882708.

The spelling of 217931138 in words is "two hundred seventeen million, nine hundred thirty-one thousand, one hundred thirty-eight".