6687406613861 has 4 divisors (see below), whose sum is σ = 6687895437324. Its totient is φ = 6686917790400.

The previous prime is 6687406613851. The next prime is 6687406613873. The reversal of 6687406613861 is 1683166047866.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6053169581761 + 634237032100 = 2460319^2 + 796390^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6687406613861 is a prime.

It is a super-2 number, since 2×6687406613861² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6687406613794 and 6687406613803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6687406613851) 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, 244391210 + ... + 244418571.

It is an arithmetic number, because the mean of its divisors is an integer number (1671973859331).

Almost surely, 2^{6687406613861} is an apocalyptic number.

It is an amenable number.

6687406613861 is a deficient number, since it is larger than the sum of its proper divisors (488823463).

6687406613861 is a wasteful number, since it uses less digits than its factorization.

6687406613861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488823462.

The product of its (nonzero) digits is 41803776, while the sum is 62.

The spelling of 6687406613861 in words is "six trillion, six hundred eighty-seven billion, four hundred six million, six hundred thirteen thousand, eight hundred sixty-one".