687645687 has 4 divisors (see below), whose sum is σ = 916860920. Its totient is φ = 458430456.

The previous prime is 687645671. The next prime is 687645731. The reversal of 687645687 is 786546786.

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

It is not a de Polignac number, because 687645687 - 2⁴ = 687645671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687645617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114607612 + ... + 114607617.

It is an arithmetic number, because the mean of its divisors is an integer number (229215230).

Almost surely, 2^687645687 is an apocalyptic number.

687645687 is a deficient number, since it is larger than the sum of its proper divisors (229215233).

687645687 is a wasteful number, since it uses less digits than its factorization.

687645687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229215232.

The product of its digits is 13547520, while the sum is 57.

The square root of 687645687 is about 26222.9991991763. Note that the first 3 decimals coincide. The cubic root of 687645687 is about 882.6494219566.

The spelling of 687645687 in words is "six hundred eighty-seven million, six hundred forty-five thousand, six hundred eighty-seven".