686139681 has 8 divisors (see below), whose sum is σ = 946399680. Its totient is φ = 441653072.

The previous prime is 686139679. The next prime is 686139683. The reversal of 686139681 is 186931686.

It is an interprime number because it is at equal distance from previous prime (686139679) and next prime (686139683).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 686139681 - 2¹ = 686139679 is a prime.

It is a super-2 number, since 2×686139681² = 941575323685563522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 686139681.

It is not an unprimeable number, because it can be changed into a prime (686139683) 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 in 7 ways as a sum of consecutive naturals, for example, 3943245 + ... + 3943418.

It is an arithmetic number, because the mean of its divisors is an integer number (118299960).

Almost surely, 2^686139681 is an apocalyptic number.

It is an amenable number.

686139681 is a deficient number, since it is larger than the sum of its proper divisors (260259999).

686139681 is a wasteful number, since it uses less digits than its factorization.

686139681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7886695.

The product of its digits is 373248, while the sum is 48.

The square root of 686139681 is about 26194.2680943752. The cubic root of 686139681 is about 882.0045903988.

The spelling of 686139681 in words is "six hundred eighty-six million, one hundred thirty-nine thousand, six hundred eighty-one".