77899999domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes with digit sum = 67.at n=6A106807Primes p with digit sums s(p) and s(s(p)) also prime, but s(s(s(p))) not prime.at n=6A213354Smallest n-digit integer x such that x + A007954(x) has n+1 digits, where A007954(x) is the product of decimal digits of x.at n=7A243219Prime numbersat n=4554051