215771 has 2 divisors, whose sum is σ = 215772. Its totient is φ = 215770.

The previous prime is 215767. The next prime is 215797. The reversal of 215771 is 177512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 215771 - 2² = 215767 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (215471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107885 + 107886.

It is an arithmetic number, because the mean of its divisors is an integer number (107886).

2²¹⁵⁷⁷¹ is an apocalyptic number.

215771 is a deficient number, since it is larger than the sum of its proper divisors (1).

215771 is an equidigital number, since it uses as much as digits as its factorization.

215771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 490, while the sum is 23.

The square root of 215771 is about 464.5115714382. The cubic root of 215771 is about 59.9787887986.

The spelling of 215771 in words is "two hundred fifteen thousand, seven hundred seventy-one".