681421 has 16 divisors (see below), whose sum is σ = 798336. Its totient is φ = 576576.

The previous prime is 681419. The next prime is 681427. The reversal of 681421 is 124186.

It is not a de Polignac number, because 681421 - 2¹ = 681419 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 681392 and 681401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681427) 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 15 ways as a sum of consecutive naturals, for example, 12831 + ... + 12883.

It is an arithmetic number, because the mean of its divisors is an integer number (49896).

2⁶⁸¹⁴²¹ is an apocalyptic number.

It is an amenable number.

681421 is a deficient number, since it is larger than the sum of its proper divisors (116915).

681421 is a wasteful number, since it uses less digits than its factorization.

681421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132.

The product of its digits is 384, while the sum is 22.

The square root of 681421 is about 825.4822832745. The cubic root of 681421 is about 87.9978046973.

The spelling of 681421 in words is "six hundred eighty-one thousand, four hundred twenty-one".