687649 has 4 divisors (see below), whose sum is σ = 691120. Its totient is φ = 684180.

The previous prime is 687647. The next prime is 687679. The reversal of 687649 is 946786.

687649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 687649 - 2¹ = 687647 is a prime.

It is a super-2 number, since 2×687649² = 945722294402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (687641) 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, 1419 + ... + 1840.

It is an arithmetic number, because the mean of its divisors is an integer number (172780).

2⁶⁸⁷⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

687649 is a deficient number, since it is larger than the sum of its proper divisors (3471).

687649 is a wasteful number, since it uses less digits than its factorization.

687649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3470.

The product of its digits is 72576, while the sum is 40.

The square root of 687649 is about 829.2460431018. The cubic root of 687649 is about 88.2650839456.

The spelling of 687649 in words is "six hundred eighty-seven thousand, six hundred forty-nine".