688421 has 4 divisors (see below), whose sum is σ = 690144. Its totient is φ = 686700.

The previous prime is 688411. The next prime is 688423. The reversal of 688421 is 124886.

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 688421 - 2⁶ = 688357 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 (688423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86 + ... + 1176.

It is an arithmetic number, because the mean of its divisors is an integer number (172536).

2⁶⁸⁸⁴²¹ is an apocalyptic number.

It is an amenable number.

688421 is a deficient number, since it is larger than the sum of its proper divisors (1723).

688421 is a wasteful number, since it uses less digits than its factorization.

688421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1722.

The product of its digits is 3072, while the sum is 29.

The square root of 688421 is about 829.7113956069. The cubic root of 688421 is about 88.2981023223.

The spelling of 688421 in words is "six hundred eighty-eight thousand, four hundred twenty-one".