686971729 has 4 divisors (see below), whose sum is σ = 692215920. Its totient is φ = 681727540.

The previous prime is 686971709. The next prime is 686971739. The reversal of 686971729 is 927179686.

686971729 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 927179686 = 2 ⋅463589843.

It is a cyclic number.

It is not a de Polignac number, because 686971729 - 2⁵ = 686971697 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 686971729.

It is not an unprimeable number, because it can be changed into a prime (686971709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2621899 + ... + 2622160.

It is an arithmetic number, because the mean of its divisors is an integer number (173053980).

Almost surely, 2^686971729 is an apocalyptic number.

It is an amenable number.

686971729 is a deficient number, since it is larger than the sum of its proper divisors (5244191).

686971729 is a wasteful number, since it uses less digits than its factorization.

686971729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5244190.

The product of its digits is 2286144, while the sum is 55.

The square root of 686971729 is about 26210.1455356509. The cubic root of 686971729 is about 882.3609676461.

The spelling of 686971729 in words is "six hundred eighty-six million, nine hundred seventy-one thousand, seven hundred twenty-nine".