687344197 has 4 divisors (see below), whose sum is σ = 687409740. Its totient is φ = 687278656.

The previous prime is 687344149. The next prime is 687344219. The reversal of 687344197 is 791443786.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 414896161 + 272448036 = 20369^2 + 16506^2 .

It is a 3-Lehmer number, since φ(687344197) divides (687344197-1)³.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687344197 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 687344197.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687344107) 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, 13108 + ... + 39325.

It is an arithmetic number, because the mean of its divisors is an integer number (171852435).

Almost surely, 2^687344197 is an apocalyptic number.

687344197 is the 13109-th decagonal number.

It is an amenable number.

687344197 is a deficient number, since it is larger than the sum of its proper divisors (65543).

687344197 is a wasteful number, since it uses less digits than its factorization.

687344197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65542.

The product of its digits is 1016064, while the sum is 49.

The square root of 687344197 is about 26217.2499892723. The cubic root of 687344197 is about 882.5204074173.

The spelling of 687344197 in words is "six hundred eighty-seven million, three hundred forty-four thousand, one hundred ninety-seven".