217920406423 has 2 divisors, whose sum is σ = 217920406424. Its totient is φ = 217920406422.

The previous prime is 217920406421. The next prime is 217920406469. The reversal of 217920406423 is 324604029712.

217920406423 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 217920406423 - 2¹ = 217920406421 is a prime.

Together with 217920406421, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217920406421) 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, 108960203211 + 108960203212.

It is an arithmetic number, because the mean of its divisors is an integer number (108960203212).

Almost surely, 2^217920406423 is an apocalyptic number.

217920406423 is a deficient number, since it is larger than the sum of its proper divisors (1).

217920406423 is an equidigital number, since it uses as much as digits as its factorization.

217920406423 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 40.

The spelling of 217920406423 in words is "two hundred seventeen billion, nine hundred twenty million, four hundred six thousand, four hundred twenty-three".