685780769 has 2 divisors, whose sum is σ = 685780770. Its totient is φ = 685780768.

The previous prime is 685780759. The next prime is 685780783. The reversal of 685780769 is 967087586.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 553990369 + 131790400 = 23537^2 + 11480^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685780769 is a prime.

It is a super-2 number, since 2×685780769² = 940590526260462722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (685780759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342890384 + 342890385.

It is an arithmetic number, because the mean of its divisors is an integer number (342890385).

Almost surely, 2^685780769 is an apocalyptic number.

It is an amenable number.

685780769 is a deficient number, since it is larger than the sum of its proper divisors (1).

685780769 is an equidigital number, since it uses as much as digits as its factorization.

685780769 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5080320, while the sum is 56.

The square root of 685780769 is about 26187.4162337562. The cubic root of 685780769 is about 881.8507746608.

The spelling of 685780769 in words is "six hundred eighty-five million, seven hundred eighty thousand, seven hundred sixty-nine".