215957138 has 4 divisors (see below), whose sum is σ = 323935710. Its totient is φ = 107978568.

The previous prime is 215957117. The next prime is 215957149. The reversal of 215957138 is 831759512.

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., 199007449 + 16949689 = 14107^2 + 4117^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 215957095 and 215957104.

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 as a sum of consecutive naturals, namely, 53989283 + ... + 53989286.

Almost surely, 2^215957138 is an apocalyptic number.

215957138 is a deficient number, since it is larger than the sum of its proper divisors (107978572).

215957138 is a wasteful number, since it uses less digits than its factorization.

215957138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107978571.

The product of its digits is 75600, while the sum is 41.

The square root of 215957138 is about 14695.4801895004. The cubic root of 215957138 is about 599.9603103376.

The spelling of 215957138 in words is "two hundred fifteen million, nine hundred fifty-seven thousand, one hundred thirty-eight".