6640397 has 2 divisors, whose sum is σ = 6640398. Its totient is φ = 6640396.

The previous prime is 6640393. The next prime is 6640409. The reversal of 6640397 is 7930466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5597956 + 1042441 = 2366^2 + 1021^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640397 - 2² = 6640393 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6640393) 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 as a sum of consecutive naturals, namely, 3320198 + 3320199.

It is an arithmetic number, because the mean of its divisors is an integer number (3320199).

Almost surely, 2^6640397 is an apocalyptic number.

It is an amenable number.

6640397 is a deficient number, since it is larger than the sum of its proper divisors (1).

6640397 is an equidigital number, since it uses as much as digits as its factorization.

6640397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 35.

The square root of 6640397 is about 2576.8967771333. The cubic root of 6640397 is about 187.9596733332.

The spelling of 6640397 in words is "six million, six hundred forty thousand, three hundred ninety-seven".