687725861 has 4 divisors (see below), whose sum is σ = 688170252. Its totient is φ = 687281472.

The previous prime is 687725849. The next prime is 687725897. The reversal of 687725861 is 168527786.

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 51122500 + 636603361 = 7150^2 + 25231^2 .

It is a cyclic number.

It is not a de Polignac number, because 687725861 - 2²² = 683531557 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 (687725561) 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, 219866 + ... + 222971.

It is an arithmetic number, because the mean of its divisors is an integer number (172042563).

Almost surely, 2^687725861 is an apocalyptic number.

It is an amenable number.

687725861 is a deficient number, since it is larger than the sum of its proper divisors (444391).

687725861 is a wasteful number, since it uses less digits than its factorization.

687725861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444390.

The product of its digits is 1128960, while the sum is 50.

The square root of 687725861 is about 26224.5278508499. The cubic root of 687725861 is about 882.6837239167.

The spelling of 687725861 in words is "six hundred eighty-seven million, seven hundred twenty-five thousand, eight hundred sixty-one".