685956421 has 2 divisors, whose sum is σ = 685956422. Its totient is φ = 685956420.

The previous prime is 685956379. The next prime is 685956451. The reversal of 685956421 is 124659586.

685956421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 384552100 + 301404321 = 19610^2 + 17361^2 .

It is a cyclic number.

It is not a de Polignac number, because 685956421 - 2¹⁹ = 685432133 is a prime.

It is a super-2 number, since 2×685956421² = 941072423022258482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685956451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342978210 + 342978211.

It is an arithmetic number, because the mean of its divisors is an integer number (342978211).

Almost surely, 2^685956421 is an apocalyptic number.

It is an amenable number.

685956421 is a deficient number, since it is larger than the sum of its proper divisors (1).

685956421 is an equidigital number, since it uses as much as digits as its factorization.

685956421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 518400, while the sum is 46.

The square root of 685956421 is about 26190.7697672291. The cubic root of 685956421 is about 881.9260589869.

The spelling of 685956421 in words is "six hundred eighty-five million, nine hundred fifty-six thousand, four hundred twenty-one".