6659021 has 2 divisors, whose sum is σ = 6659022. Its totient is φ = 6659020.

The previous prime is 6658999. The next prime is 6659027. The reversal of 6659021 is 1209566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5470921 + 1188100 = 2339^2 + 1090^2 .

It is a cyclic number.

It is not a de Polignac number, because 6659021 - 2¹⁰ = 6657997 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6659027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3329510 + 3329511.

It is an arithmetic number, because the mean of its divisors is an integer number (3329511).

Almost surely, 2^6659021 is an apocalyptic number.

It is an amenable number.

6659021 is a deficient number, since it is larger than the sum of its proper divisors (1).

6659021 is an equidigital number, since it uses as much as digits as its factorization.

6659021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 6659021 is about 2580.5078957446. The cubic root of 6659021 is about 188.1352297760.

The spelling of 6659021 in words is "six million, six hundred fifty-nine thousand, twenty-one".