6640657 has 2 divisors, whose sum is σ = 6640658. Its totient is φ = 6640656.

The previous prime is 6640651. The next prime is 6640663. The reversal of 6640657 is 7560466.

It is a balanced prime because it is at equal distance from previous prime (6640651) and next prime (6640663).

It can be written as a sum of positive squares in only one way, i.e., 4999696 + 1640961 = 2236^2 + 1281^2 .

It is a cyclic number.

It is not a de Polignac number, because 6640657 - 2¹⁵ = 6607889 is a prime.

6640657 is a lucky number.

It is a nialpdrome in base 16.

It is not a weakly prime, because it can be changed into another prime (6640651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3320328 + 3320329.

It is an arithmetic number, because the mean of its divisors is an integer number (3320329).

Almost surely, 2^6640657 is an apocalyptic number.

It is an amenable number.

6640657 is a deficient number, since it is larger than the sum of its proper divisors (1).

6640657 is an equidigital number, since it uses as much as digits as its factorization.

6640657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 6640657 is about 2576.9472249156. The cubic root of 6640657 is about 187.9621264434.

The spelling of 6640657 in words is "six million, six hundred forty thousand, six hundred fifty-seven".