686866815381 has 4 divisors (see below), whose sum is σ = 915822420512. Its totient is φ = 457911210252.

The previous prime is 686866815379. The next prime is 686866815421. The reversal of 686866815381 is 183518668686.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 686866815381 - 2¹ = 686866815379 is a prime.

It is a super-2 number, since 2×686866815381² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686866815781) 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, 114477802561 + ... + 114477802566.

It is an arithmetic number, because the mean of its divisors is an integer number (228955605128).

Almost surely, 2^686866815381 is an apocalyptic number.

It is an amenable number.

686866815381 is a deficient number, since it is larger than the sum of its proper divisors (228955605131).

686866815381 is a wasteful number, since it uses less digits than its factorization.

686866815381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228955605130.

The product of its digits is 79626240, while the sum is 66.

The spelling of 686866815381 in words is "six hundred eighty-six billion, eight hundred sixty-six million, eight hundred fifteen thousand, three hundred eighty-one".