6641981 has 8 divisors (see below), whose sum is σ = 6901560. Its totient is φ = 6386688.

The previous prime is 6641977. The next prime is 6641983. The reversal of 6641981 is 1891466.

It can be written as a sum of positive squares in 4 ways, for example, as 2402500 + 4239481 = 1550^2 + 2059^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6641981 - 2² = 6641977 is a prime.

It is a super-2 number, since 2×6641981² = 88231823208722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6641983) 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 7 ways as a sum of consecutive naturals, for example, 2285 + ... + 4301.

It is an arithmetic number, because the mean of its divisors is an integer number (862695).

Almost surely, 2^6641981 is an apocalyptic number.

It is an amenable number.

6641981 is a deficient number, since it is larger than the sum of its proper divisors (259579).

6641981 is a wasteful number, since it uses less digits than its factorization.

6641981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2143.

The product of its digits is 10368, while the sum is 35.

The square root of 6641981 is about 2577.2041052272. The cubic root of 6641981 is about 187.9746174423.

The spelling of 6641981 in words is "six million, six hundred forty-one thousand, nine hundred eighty-one".