6631781 has 4 divisors (see below), whose sum is σ = 7141932. Its totient is φ = 6121632.

The previous prime is 6631763. The next prime is 6631789. The reversal of 6631781 is 1871366.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 919681 + 5712100 = 959^2 + 2390^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6631781 is a prime.

It is a super-2 number, since 2×6631781² = 87961038463922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6631789) 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 3 ways as a sum of consecutive naturals, for example, 255056 + ... + 255081.

It is an arithmetic number, because the mean of its divisors is an integer number (1785483).

Almost surely, 2^6631781 is an apocalyptic number.

It is an amenable number.

6631781 is a deficient number, since it is larger than the sum of its proper divisors (510151).

6631781 is a wasteful number, since it uses less digits than its factorization.

6631781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510150.

The product of its digits is 6048, while the sum is 32.

The square root of 6631781 is about 2575.2244562368. The cubic root of 6631781 is about 187.8783447884.

The spelling of 6631781 in words is "six million, six hundred thirty-one thousand, seven hundred eighty-one".