217201997 has 2 divisors, whose sum is σ = 217201998. Its totient is φ = 217201996.

The previous prime is 217201927. The next prime is 217202017. The reversal of 217201997 is 799102712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216855076 + 346921 = 14726^2 + 589^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217201997 is a prime.

It is equal to p_11976932 and since 217201997 and 11976932 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 217201997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217201927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108600998 + 108600999.

It is an arithmetic number, because the mean of its divisors is an integer number (108600999).

Almost surely, 2^217201997 is an apocalyptic number.

It is an amenable number.

217201997 is a deficient number, since it is larger than the sum of its proper divisors (1).

217201997 is an equidigital number, since it uses as much as digits as its factorization.

217201997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15876, while the sum is 38.

The square root of 217201997 is about 14737.7744927788. The cubic root of 217201997 is about 601.1109020767.

The spelling of 217201997 in words is "two hundred seventeen million, two hundred one thousand, nine hundred ninety-seven".