215381 has 2 divisors, whose sum is σ = 215382.
Its totient is φ = 215380.
The previous prime is 215359. The next prime is 215389. The reversal of 215381 is 183512.
215381 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 152881 + 62500 = 391^2 + 250^2
It is a cyclic number.
It is not a de Polignac number, because 215381 - 26 = 215317 is a prime.
It is a super-2 number, since 2×2153812 = 92777950322, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (215389) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107690 + 107691.
It is an arithmetic number, because the mean of its divisors is an integer number (107691).
2215381 is an apocalyptic number.
It is an amenable number.
215381 is a deficient number, since it is larger than the sum of its proper divisors (1).
215381 is an equidigital number, since it uses as much as digits as its factorization.
215381 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 240, while the sum is 20.
The square root of 215381 is about 464.0915857888.
The cubic root of 215381 is about 59.9426303481.
Adding to 215381 its reverse (183512), we get a palindrome (398893).
The spelling of 215381 in words is "two hundred fifteen thousand, three hundred eighty-one".