687780 has 36 divisors (see below), whose sum is σ = 2086812. Its totient is φ = 183360.

The previous prime is 687779. The next prime is 687787. The reversal of 687780 is 87786.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 451584 + 236196 = 672^2 + 486^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (687787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1731 + ... + 2090.

It is an arithmetic number, because the mean of its divisors is an integer number (57967).

2⁶⁸⁷⁷⁸⁰ is an apocalyptic number.

687780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

687780 is an abundant number, since it is smaller than the sum of its proper divisors (1399032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

687780 is a wasteful number, since it uses less digits than its factorization.

687780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3836 (or 3831 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 687780 is about 829.3250267537. The cubic root of 687780 is about 88.2706885452.

The spelling of 687780 in words is "six hundred eighty-seven thousand, seven hundred eighty".