6618991 has 2 divisors, whose sum is σ = 6618992. Its totient is φ = 6618990.

The previous prime is 6618979. The next prime is 6619021. The reversal of 6618991 is 1998166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6618991 - 2⁵ = 6618959 is a prime.

It is a super-2 number, since 2×6618991² = 87622083716162, which contains 22 as substring.

It is a Chen prime.

6618991 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6618901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3309495 + 3309496.

It is an arithmetic number, because the mean of its divisors is an integer number (3309496).

Almost surely, 2^6618991 is an apocalyptic number.

6618991 is a deficient number, since it is larger than the sum of its proper divisors (1).

6618991 is an equidigital number, since it uses as much as digits as its factorization.

6618991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 40.

The square root of 6618991 is about 2572.7399790884. The cubic root of 6618991 is about 187.7574868336.

The spelling of 6618991 in words is "six million, six hundred eighteen thousand, nine hundred ninety-one".