6551921 has 2 divisors, whose sum is σ = 6551922. Its totient is φ = 6551920.

The previous prime is 6551917. The next prime is 6551947. The reversal of 6551921 is 1291556.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3783025 + 2768896 = 1945^2 + 1664^2 .

It is a cyclic number.

It is not a de Polignac number, because 6551921 - 2² = 6551917 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (6551821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3275960 + 3275961.

It is an arithmetic number, because the mean of its divisors is an integer number (3275961).

Almost surely, 2^6551921 is an apocalyptic number.

It is an amenable number.

6551921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6551921 is an equidigital number, since it uses as much as digits as its factorization.

6551921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2700, while the sum is 29.

The square root of 6551921 is about 2559.6720493063. The cubic root of 6551921 is about 187.1211526769.

The spelling of 6551921 in words is "six million, five hundred fifty-one thousand, nine hundred twenty-one".