6681621 has 4 divisors (see below), whose sum is σ = 8908832. Its totient is φ = 4454412.

The previous prime is 6681589. The next prime is 6681637. The reversal of 6681621 is 1261866.

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 not a de Polignac number, because 6681621 - 2⁵ = 6681589 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

6681621 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6681671) 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, 1113601 + ... + 1113606.

It is an arithmetic number, because the mean of its divisors is an integer number (2227208).

Almost surely, 2^6681621 is an apocalyptic number.

It is an amenable number.

6681621 is a deficient number, since it is larger than the sum of its proper divisors (2227211).

6681621 is a wasteful number, since it uses less digits than its factorization.

6681621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2227210.

The product of its digits is 3456, while the sum is 30.

The square root of 6681621 is about 2584.8831695069. The cubic root of 6681621 is about 188.3478263488.

The spelling of 6681621 in words is "six million, six hundred eighty-one thousand, six hundred twenty-one".