681478409 has 2 divisors, whose sum is σ = 681478410. Its totient is φ = 681478408.

The previous prime is 681478393. The next prime is 681478417. The reversal of 681478409 is 904874186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 679749184 + 1729225 = 26072^2 + 1315^2 .

It is a cyclic number.

It is not a de Polignac number, because 681478409 - 2⁴ = 681478393 is a prime.

It is not a weakly prime, because it can be changed into another prime (681478459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340739204 + 340739205.

It is an arithmetic number, because the mean of its divisors is an integer number (340739205).

Almost surely, 2^681478409 is an apocalyptic number.

It is an amenable number.

681478409 is a deficient number, since it is larger than the sum of its proper divisors (1).

681478409 is an equidigital number, since it uses as much as digits as its factorization.

681478409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 387072, while the sum is 47.

The square root of 681478409 is about 26105.1414284619. The cubic root of 681478409 is about 880.0027586863.

The spelling of 681478409 in words is "six hundred eighty-one million, four hundred seventy-eight thousand, four hundred nine".