685548781 has 2 divisors, whose sum is σ = 685548782. Its totient is φ = 685548780.

The previous prime is 685548751. The next prime is 685548791. The reversal of 685548781 is 187845586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 562116681 + 123432100 = 23709^2 + 11110^2 .

It is a cyclic number.

It is not a de Polignac number, because 685548781 - 2¹⁷ = 685417709 is a prime.

It is a super-3 number, since 3×685548781³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685548751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342774390 + 342774391.

It is an arithmetic number, because the mean of its divisors is an integer number (342774391).

Almost surely, 2^685548781 is an apocalyptic number.

It is an amenable number.

685548781 is a deficient number, since it is larger than the sum of its proper divisors (1).

685548781 is an equidigital number, since it uses as much as digits as its factorization.

685548781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2150400, while the sum is 52.

The square root of 685548781 is about 26182.9864797735. The cubic root of 685548781 is about 881.7513250604.

The spelling of 685548781 in words is "six hundred eighty-five million, five hundred forty-eight thousand, seven hundred eighty-one".