681642449 has 2 divisors, whose sum is σ = 681642450. Its totient is φ = 681642448.

The previous prime is 681642439. The next prime is 681642469. The reversal of 681642449 is 944246186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 370755025 + 310887424 = 19255^2 + 17632^2 .

It is a cyclic number.

It is not a de Polignac number, because 681642449 - 2⁴ = 681642433 is a prime.

It is not a weakly prime, because it can be changed into another prime (681642439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340821224 + 340821225.

It is an arithmetic number, because the mean of its divisors is an integer number (340821225).

Almost surely, 2^681642449 is an apocalyptic number.

It is an amenable number.

681642449 is a deficient number, since it is larger than the sum of its proper divisors (1).

681642449 is an equidigital number, since it uses as much as digits as its factorization.

681642449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 331776, while the sum is 44.

The square root of 681642449 is about 26108.2831492230. The cubic root of 681642449 is about 880.0733620830.

The spelling of 681642449 in words is "six hundred eighty-one million, six hundred forty-two thousand, four hundred forty-nine".