8405921 has 2 divisors, whose sum is σ = 8405922. Its totient is φ = 8405920.

The previous prime is 8405899. The next prime is 8405951. The reversal of 8405921 is 1295048.

8405921 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6553600 + 1852321 = 2560^2 + 1361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8405921 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 (8405951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4202960 + 4202961.

It is an arithmetic number, because the mean of its divisors is an integer number (4202961).

Almost surely, 2^8405921 is an apocalyptic number.

It is an amenable number.

8405921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8405921 is an equidigital number, since it uses as much as digits as its factorization.

8405921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 8405921 is about 2899.2966388419. The cubic root of 8405921 is about 203.3270227072.

The spelling of 8405921 in words is "eight million, four hundred five thousand, nine hundred twenty-one".