405504221 has 2 divisors, whose sum is σ = 405504222. Its totient is φ = 405504220.

The previous prime is 405504173. The next prime is 405504241. The reversal of 405504221 is 122405504.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 404572996 + 931225 = 20114^2 + 965^2 .

It is a cyclic number.

It is not a de Polignac number, because 405504221 - 2⁶ = 405504157 is a prime.

It is a Chen prime.

It is equal to p_21614018 and since 405504221 and 21614018 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (405504241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202752110 + 202752111.

It is an arithmetic number, because the mean of its divisors is an integer number (202752111).

Almost surely, 2^405504221 is an apocalyptic number.

It is an amenable number.

405504221 is a deficient number, since it is larger than the sum of its proper divisors (1).

405504221 is an equidigital number, since it uses as much as digits as its factorization.

405504221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 405504221 is about 20137.1353722420. The cubic root of 405504221 is about 740.1705359337.

Adding to 405504221 its reverse (122405504), we get a palindrome (527909725).

The spelling of 405504221 in words is "four hundred five million, five hundred four thousand, two hundred twenty-one".