685658261 has 2 divisors, whose sum is σ = 685658262. Its totient is φ = 685658260.

The previous prime is 685658249. The next prime is 685658291. The reversal of 685658261 is 162856586.

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., 621754225 + 63904036 = 24935^2 + 7994^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685658261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685658201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342829130 + 342829131.

It is an arithmetic number, because the mean of its divisors is an integer number (342829131).

Almost surely, 2^685658261 is an apocalyptic number.

It is an amenable number.

685658261 is a deficient number, since it is larger than the sum of its proper divisors (1).

685658261 is an equidigital number, since it uses as much as digits as its factorization.

685658261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 691200, while the sum is 47.

The square root of 685658261 is about 26185.0770669097. The cubic root of 685658261 is about 881.7982602066.

The spelling of 685658261 in words is "six hundred eighty-five million, six hundred fifty-eight thousand, two hundred sixty-one".