686390819 has 2 divisors, whose sum is σ = 686390820. Its totient is φ = 686390818.

The previous prime is 686390777. The next prime is 686390839. The reversal of 686390819 is 918093686.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686390819 is a prime.

It is a super-2 number, since 2×686390819² = 942264712814981522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (686390839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343195409 + 343195410.

It is an arithmetic number, because the mean of its divisors is an integer number (343195410).

Almost surely, 2^686390819 is an apocalyptic number.

686390819 is a deficient number, since it is larger than the sum of its proper divisors (1).

686390819 is an equidigital number, since it uses as much as digits as its factorization.

686390819 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 559872, while the sum is 50.

The square root of 686390819 is about 26199.0614144858. The cubic root of 686390819 is about 882.1121864932.

The spelling of 686390819 in words is "six hundred eighty-six million, three hundred ninety thousand, eight hundred nineteen".