681621 has 4 divisors (see below), whose sum is σ = 908832. Its totient is φ = 454412.

The previous prime is 681613. The next prime is 681623. The reversal of 681621 is 126186.

681621 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 681621 - 2³ = 681613 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 681591 and 681600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681623) 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, 113601 + ... + 113606.

It is an arithmetic number, because the mean of its divisors is an integer number (227208).

2⁶⁸¹⁶²¹ is an apocalyptic number.

It is an amenable number.

681621 is a deficient number, since it is larger than the sum of its proper divisors (227211).

681621 is a wasteful number, since it uses less digits than its factorization.

681621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227210.

The product of its digits is 576, while the sum is 24.

The square root of 681621 is about 825.6034156906. The cubic root of 681621 is about 88.0064131001.

The spelling of 681621 in words is "six hundred eighty-one thousand, six hundred twenty-one".