405808421 has 2 divisors, whose sum is σ = 405808422. Its totient is φ = 405808420.

The previous prime is 405808399. The next prime is 405808427. The reversal of 405808421 is 124808504.

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., 403809025 + 1999396 = 20095^2 + 1414^2 .

It is a cyclic number.

It is not a de Polignac number, because 405808421 - 2⁶ = 405808357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (405808427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202904210 + 202904211.

It is an arithmetic number, because the mean of its divisors is an integer number (202904211).

Almost surely, 2^405808421 is an apocalyptic number.

It is an amenable number.

405808421 is a deficient number, since it is larger than the sum of its proper divisors (1).

405808421 is an equidigital number, since it uses as much as digits as its factorization.

405808421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10240, while the sum is 32.

The square root of 405808421 is about 20144.6871656027. The cubic root of 405808421 is about 740.3555760110.

The spelling of 405808421 in words is "four hundred five million, eight hundred eight thousand, four hundred twenty-one".