687949 has 2 divisors, whose sum is σ = 687950. Its totient is φ = 687948.

The previous prime is 687931. The next prime is 687961. The reversal of 687949 is 949786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 455625 + 232324 = 675^2 + 482^2 .

It is a cyclic number.

It is not a de Polignac number, because 687949 - 2⁵ = 687917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687749) 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, 343974 + 343975.

It is an arithmetic number, because the mean of its divisors is an integer number (343975).

2⁶⁸⁷⁹⁴⁹ is an apocalyptic number.

It is an amenable number.

687949 is a deficient number, since it is larger than the sum of its proper divisors (1).

687949 is an equidigital number, since it uses as much as digits as its factorization.

687949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

The square root of 687949 is about 829.4269105834. The cubic root of 687949 is about 88.2779178553.

The spelling of 687949 in words is "six hundred eighty-seven thousand, nine hundred forty-nine".