217623979 has 2 divisors, whose sum is σ = 217623980. Its totient is φ = 217623978.

The previous prime is 217623977. The next prime is 217623997. The reversal of 217623979 is 979326712.

Together with next prime (217623997) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 217623979 - 2¹ = 217623977 is a prime.

Together with 217623977, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (217623971) 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, 108811989 + 108811990.

It is an arithmetic number, because the mean of its divisors is an integer number (108811990).

Almost surely, 2^217623979 is an apocalyptic number.

217623979 is a deficient number, since it is larger than the sum of its proper divisors (1).

217623979 is an equidigital number, since it uses as much as digits as its factorization.

217623979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 285768, while the sum is 46.

The square root of 217623979 is about 14752.0838866921. The cubic root of 217623979 is about 601.4999314773.

The spelling of 217623979 in words is "two hundred seventeen million, six hundred twenty-three thousand, nine hundred seventy-nine".