217970887 has 2 divisors, whose sum is σ = 217970888. Its totient is φ = 217970886.

The previous prime is 217970867. The next prime is 217970911. The reversal of 217970887 is 788079712.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217970887 is a prime.

It is a super-2 number, since 2×217970887² = 95022615159133538, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 217970887.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217970867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108985443 + 108985444.

It is an arithmetic number, because the mean of its divisors is an integer number (108985444).

Almost surely, 2^217970887 is an apocalyptic number.

217970887 is a deficient number, since it is larger than the sum of its proper divisors (1).

217970887 is an equidigital number, since it uses as much as digits as its factorization.

217970887 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 395136, while the sum is 49.

The square root of 217970887 is about 14763.8371367338. The cubic root of 217970887 is about 601.8193729310.

The spelling of 217970887 in words is "two hundred seventeen million, nine hundred seventy thousand, eight hundred eighty-seven".