6601921 has 2 divisors, whose sum is σ = 6601922. Its totient is φ = 6601920.

The previous prime is 6601909. The next prime is 6601927. The reversal of 6601921 is 1291066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5125696 + 1476225 = 2264^2 + 1215^2 .

It is a cyclic number.

It is not a de Polignac number, because 6601921 - 2¹³ = 6593729 is a prime.

6601921 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (6601927) 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, 3300960 + 3300961.

It is an arithmetic number, because the mean of its divisors is an integer number (3300961).

Almost surely, 2^6601921 is an apocalyptic number.

It is an amenable number.

6601921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6601921 is an equidigital number, since it uses as much as digits as its factorization.

6601921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 6601921 is about 2569.4203626499. The cubic root of 6601921 is about 187.5959426021.

Adding to 6601921 its reverse (1291066), we get a palindrome (7892987).

The spelling of 6601921 in words is "six million, six hundred one thousand, nine hundred twenty-one".