216997 has 4 divisors (see below), whose sum is σ = 236736. Its totient is φ = 197260.

The previous prime is 216991. The next prime is 217001. The reversal of 216997 is 799612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216997 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216991) 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 in 3 ways as a sum of consecutive naturals, for example, 9853 + ... + 9874.

It is an arithmetic number, because the mean of its divisors is an integer number (59184).

2²¹⁶⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

216997 is a deficient number, since it is larger than the sum of its proper divisors (19739).

216997 is a wasteful number, since it uses less digits than its factorization.

216997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19738.

The product of its digits is 6804, while the sum is 34.

The square root of 216997 is about 465.8293679020. The cubic root of 216997 is about 60.0921731442.

The spelling of 216997 in words is "two hundred sixteen thousand, nine hundred ninety-seven".