685280521 has 2 divisors, whose sum is σ = 685280522. Its totient is φ = 685280520.

The previous prime is 685280473. The next prime is 685280567. The reversal of 685280521 is 125082586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 449228025 + 236052496 = 21195^2 + 15364^2 .

It is a cyclic number.

It is not a de Polignac number, because 685280521 - 2¹⁷ = 685149449 is a prime.

It is not a weakly prime, because it can be changed into another prime (685280021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342640260 + 342640261.

It is an arithmetic number, because the mean of its divisors is an integer number (342640261).

Almost surely, 2^685280521 is an apocalyptic number.

It is an amenable number.

685280521 is a deficient number, since it is larger than the sum of its proper divisors (1).

685280521 is an equidigital number, since it uses as much as digits as its factorization.

685280521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38400, while the sum is 37.

The square root of 685280521 is about 26177.8631862878. The cubic root of 685280521 is about 881.6362982493.

The spelling of 685280521 in words is "six hundred eighty-five million, two hundred eighty thousand, five hundred twenty-one".