685787917 has 2 divisors, whose sum is σ = 685787918. Its totient is φ = 685787916.

The previous prime is 685787899. The next prime is 685787981. The reversal of 685787917 is 719787586.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 410427081 + 275360836 = 20259^2 + 16594^2 .

It is a cyclic number.

It is not a de Polignac number, because 685787917 - 2⁷ = 685787789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685787117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342893958 + 342893959.

It is an arithmetic number, because the mean of its divisors is an integer number (342893959).

Almost surely, 2^685787917 is an apocalyptic number.

It is an amenable number.

685787917 is a deficient number, since it is larger than the sum of its proper divisors (1).

685787917 is an equidigital number, since it uses as much as digits as its factorization.

685787917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5927040, while the sum is 58.

The square root of 685787917 is about 26187.5527111641. The cubic root of 685787917 is about 881.8538385396.

The spelling of 685787917 in words is "six hundred eighty-five million, seven hundred eighty-seven thousand, nine hundred seventeen".