681949 has 2 divisors, whose sum is σ = 681950. Its totient is φ = 681948.

The previous prime is 681943. The next prime is 681971. The reversal of 681949 is 949186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 573049 + 108900 = 757^2 + 330^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681949 is a prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681943) 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, 340974 + 340975.

It is an arithmetic number, because the mean of its divisors is an integer number (340975).

2⁶⁸¹⁹⁴⁹ is an apocalyptic number.

It is an amenable number.

681949 is a deficient number, since it is larger than the sum of its proper divisors (1).

681949 is an equidigital number, since it uses as much as digits as its factorization.

681949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 37.

The square root of 681949 is about 825.8020343884. The cubic root of 681949 is about 88.0205272362.

The spelling of 681949 in words is "six hundred eighty-one thousand, nine hundred forty-nine".