405252781 has 2 divisors, whose sum is σ = 405252782. Its totient is φ = 405252780.

The previous prime is 405252637. The next prime is 405252811. The reversal of 405252781 is 187252504.

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., 260531881 + 144720900 = 16141^2 + 12030^2 .

It is a cyclic number.

It is not a de Polignac number, because 405252781 - 2⁹ = 405252269 is a prime.

It is a super-4 number, since 4×405252781⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (405252581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202626390 + 202626391.

It is an arithmetic number, because the mean of its divisors is an integer number (202626391).

Almost surely, 2^405252781 is an apocalyptic number.

It is an amenable number.

405252781 is a deficient number, since it is larger than the sum of its proper divisors (1).

405252781 is an equidigital number, since it uses as much as digits as its factorization.

405252781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 22400, while the sum is 34.

The square root of 405252781 is about 20130.8912122638. The cubic root of 405252781 is about 740.0175190642.

The spelling of 405252781 in words is "four hundred five million, two hundred fifty-two thousand, seven hundred eighty-one".