686665002091 has 4 divisors (see below), whose sum is σ = 702633955672. Its totient is φ = 670696048512.

The previous prime is 686665002061. The next prime is 686665002113. The reversal of 686665002091 is 190200566686.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 686665002091 - 2⁵ = 686665002059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686665002061) 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, 7984476726 + ... + 7984476811.

It is an arithmetic number, because the mean of its divisors is an integer number (175658488918).

Almost surely, 2^686665002091 is an apocalyptic number.

686665002091 is a deficient number, since it is larger than the sum of its proper divisors (15968953581).

686665002091 is a wasteful number, since it uses less digits than its factorization.

686665002091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15968953580.

The product of its (nonzero) digits is 933120, while the sum is 49.

The spelling of 686665002091 in words is "six hundred eighty-six billion, six hundred sixty-five million, two thousand, ninety-one".