215684138 has 4 divisors (see below), whose sum is σ = 323526210. Its totient is φ = 107842068.

The previous prime is 215684129. The next prime is 215684159. The reversal of 215684138 is 831486512.

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

It can be written as a sum of positive squares in only one way, i.e., 135885649 + 79798489 = 11657^2 + 8933^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 53921033 + ... + 53921036.

Almost surely, 2^215684138 is an apocalyptic number.

215684138 is a deficient number, since it is larger than the sum of its proper divisors (107842072).

215684138 is a wasteful number, since it uses less digits than its factorization.

215684138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107842071.

The product of its digits is 46080, while the sum is 38.

The square root of 215684138 is about 14686.1886818875. The cubic root of 215684138 is about 599.7073925098.

The spelling of 215684138 in words is "two hundred fifteen million, six hundred eighty-four thousand, one hundred thirty-eight".