216971791 has 2 divisors, whose sum is σ = 216971792. Its totient is φ = 216971790.

The previous prime is 216971767. The next prime is 216971801. The reversal of 216971791 is 197179612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216971791 - 2¹¹ = 216969743 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216971701) by changing a digit.

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, 108485895 + 108485896.

It is an arithmetic number, because the mean of its divisors is an integer number (108485896).

Almost surely, 2^216971791 is an apocalyptic number.

216971791 is a deficient number, since it is larger than the sum of its proper divisors (1).

216971791 is an equidigital number, since it uses as much as digits as its factorization.

216971791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 47628, while the sum is 43.

The square root of 216971791 is about 14729.9623556885. The cubic root of 216971791 is about 600.8984604247.

The spelling of 216971791 in words is "two hundred sixteen million, nine hundred seventy-one thousand, seven hundred ninety-one".