686668010491 has 16 divisors (see below), whose sum is σ = 701944278048. Its totient is φ = 671531212800.

The previous prime is 686668010489. The next prime is 686668010513. The reversal of 686668010491 is 194010866686.

It is a cyclic number.

It is not a de Polignac number, because 686668010491 - 2¹ = 686668010489 is a prime.

It is a super-2 number, since 2×686668010491² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686668710491) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8440776 + ... + 8521738.

It is an arithmetic number, because the mean of its divisors is an integer number (43871517378).

Almost surely, 2^686668010491 is an apocalyptic number.

686668010491 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

686668010491 is a deficient number, since it is larger than the sum of its proper divisors (15276267557).

686668010491 is a wasteful number, since it uses less digits than its factorization.

686668010491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81822.

The product of its (nonzero) digits is 2985984, while the sum is 55.

The spelling of 686668010491 in words is "six hundred eighty-six billion, six hundred sixty-eight million, ten thousand, four hundred ninety-one".