6638491 has 2 divisors, whose sum is σ = 6638492. Its totient is φ = 6638490.

The previous prime is 6638473. The next prime is 6638497. The reversal of 6638491 is 1948366.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6638491 - 2⁵ = 6638459 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6638491.

It is not a weakly prime, because it can be changed into another prime (6638497) 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 as a sum of consecutive naturals, namely, 3319245 + 3319246.

It is an arithmetic number, because the mean of its divisors is an integer number (3319246).

Almost surely, 2^6638491 is an apocalyptic number.

6638491 is a deficient number, since it is larger than the sum of its proper divisors (1).

6638491 is an equidigital number, since it uses as much as digits as its factorization.

6638491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 37.

The square root of 6638491 is about 2576.5269259218. The cubic root of 6638491 is about 187.9416881927.

The spelling of 6638491 in words is "six million, six hundred thirty-eight thousand, four hundred ninety-one".