686041677721 has 2 divisors, whose sum is σ = 686041677722. Its totient is φ = 686041677720.

The previous prime is 686041677707. The next prime is 686041677743. The reversal of 686041677721 is 127776140686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 530364084121 + 155677593600 = 728261^2 + 394560^2 .

It is a cyclic number.

It is not a de Polignac number, because 686041677721 - 2⁷ = 686041677593 is a prime.

It is a super-4 number, since 4×686041677721⁴ (a number of 48 digits) contains 4444 as substring.

It is not a weakly prime, because it can be changed into another prime (686041677701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343020838860 + 343020838861.

It is an arithmetic number, because the mean of its divisors is an integer number (343020838861).

Almost surely, 2^686041677721 is an apocalyptic number.

It is an amenable number.

686041677721 is a deficient number, since it is larger than the sum of its proper divisors (1).

686041677721 is an equidigital number, since it uses as much as digits as its factorization.

686041677721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4741632, while the sum is 55.

The spelling of 686041677721 in words is "six hundred eighty-six billion, forty-one million, six hundred seventy-seven thousand, seven hundred twenty-one".