873699809

This number is a prime.

873699809 is the sum of nine seven-digit primes with repdigit indices, i.e., 873699809 = 17329489 + 36312197 + 55911127 + 75906931 + 96210113 + 116743349 + 137478503 + 158383429 + 179424671 = prime(1111111) + prime(2222222) + prime(3333333) + prime(4444444) + prime(5555555) + prime(6666666) + prime(7777777) + prime(8888888) + prime(9999999). [Ikemoto]