686694991 has 8 divisors (see below), whose sum is σ = 727819344. Its totient is φ = 645651840.

The previous prime is 686694989. The next prime is 686695001. The reversal of 686694991 is 199496686.

686694991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 686694991 - 2¹ = 686694989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686694901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2425 + ... + 37138.

It is an arithmetic number, because the mean of its divisors is an integer number (90977418).

Almost surely, 2^686694991 is an apocalyptic number.

686694991 is a deficient number, since it is larger than the sum of its proper divisors (41124353).

686694991 is a wasteful number, since it uses less digits than its factorization.

686694991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40601.

The product of its digits is 5038848, while the sum is 58.

The square root of 686694991 is about 26204.8657886279. The cubic root of 686694991 is about 882.2424690262.

The spelling of 686694991 in words is "six hundred eighty-six million, six hundred ninety-four thousand, nine hundred ninety-one".