681840461 has 2 divisors, whose sum is σ = 681840462. Its totient is φ = 681840460.

The previous prime is 681840457. The next prime is 681840463. The reversal of 681840461 is 164048186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 473932900 + 207907561 = 21770^2 + 14419^2 .

It is a cyclic number.

It is not a de Polignac number, because 681840461 - 2² = 681840457 is a prime.

Together with 681840463, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681840463) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340920230 + 340920231.

It is an arithmetic number, because the mean of its divisors is an integer number (340920231).

Almost surely, 2^681840461 is an apocalyptic number.

It is an amenable number.

681840461 is a deficient number, since it is larger than the sum of its proper divisors (1).

681840461 is an equidigital number, since it uses as much as digits as its factorization.

681840461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36864, while the sum is 38.

The square root of 681840461 is about 26112.0750037219. The cubic root of 681840461 is about 880.1585720614.

The spelling of 681840461 in words is "six hundred eighty-one million, eight hundred forty thousand, four hundred sixty-one".