684739729 has 4 divisors (see below), whose sum is σ = 701440740. Its totient is φ = 668038720.

The previous prime is 684739717. The next prime is 684739747. The reversal of 684739729 is 927937486.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 182979729 + 501760000 = 13527^2 + 22400^2 .

It is a cyclic number.

It is not a de Polignac number, because 684739729 - 2²¹ = 682642577 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 684739729.

It is not an unprimeable number, because it can be changed into a prime (684739789) 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 in 3 ways as a sum of consecutive naturals, for example, 8350444 + ... + 8350525.

It is an arithmetic number, because the mean of its divisors is an integer number (175360185).

Almost surely, 2^684739729 is an apocalyptic number.

It is an amenable number.

684739729 is a deficient number, since it is larger than the sum of its proper divisors (16701011).

684739729 is a wasteful number, since it uses less digits than its factorization.

684739729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16701010.

The product of its digits is 4572288, while the sum is 55.

The square root of 684739729 is about 26167.5319623384. The cubic root of 684739729 is about 881.4043215549.

The spelling of 684739729 in words is "six hundred eighty-four million, seven hundred thirty-nine thousand, seven hundred twenty-nine".