687421 has 6 divisors (see below), whose sum is σ = 799710. Its totient is φ = 589176.

The previous prime is 687413. The next prime is 687431. The reversal of 687421 is 124786.

It can be written as a sum of positive squares in only one way, i.e., 396900 + 290521 = 630^2 + 539^2 .

It is not a de Polignac number, because 687421 - 2³ = 687413 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 687421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6966 + ... + 7063.

It is an arithmetic number, because the mean of its divisors is an integer number (133285).

2⁶⁸⁷⁴²¹ is an apocalyptic number.

It is an amenable number.

687421 is a deficient number, since it is larger than the sum of its proper divisors (112289).

687421 is a wasteful number, since it uses less digits than its factorization.

687421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14043 (or 14036 counting only the distinct ones).

The product of its digits is 2688, while the sum is 28.

The square root of 687421 is about 829.1085574278. The cubic root of 687421 is about 88.2553276777.

The spelling of 687421 in words is "six hundred eighty-seven thousand, four hundred twenty-one".