684919819 has 2 divisors, whose sum is σ = 684919820. Its totient is φ = 684919818.

The previous prime is 684919793. The next prime is 684919853. The reversal of 684919819 is 918919486.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 684919819 - 2¹¹ = 684917771 is a prime.

It is a super-2 number, since 2×684919819² = 938230316917985522, 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 684919819.

It is not a weakly prime, because it can be changed into another prime (684919219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342459909 + 342459910.

It is an arithmetic number, because the mean of its divisors is an integer number (342459910).

Almost surely, 2^684919819 is an apocalyptic number.

684919819 is a deficient number, since it is larger than the sum of its proper divisors (1).

684919819 is an equidigital number, since it uses as much as digits as its factorization.

684919819 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1119744, while the sum is 55.

The square root of 684919819 is about 26170.9728325104. The cubic root of 684919819 is about 881.4815860413.

The spelling of 684919819 in words is "six hundred eighty-four million, nine hundred nineteen thousand, eight hundred nineteen".