421806856417 has 2 divisors, whose sum is σ = 421806856418. Its totient is φ = 421806856416.

The previous prime is 421806856349. The next prime is 421806856423. The reversal of 421806856417 is 714658608124.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 397257920656 + 24548935761 = 630284^2 + 156681^2 .

It is a cyclic number.

It is not a de Polignac number, because 421806856417 - 2²⁷ = 421672638689 is a prime.

It is not a weakly prime, because it can be changed into another prime (421806856517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210903428208 + 210903428209.

It is an arithmetic number, because the mean of its divisors is an integer number (210903428209).

Almost surely, 2^421806856417 is an apocalyptic number.

It is an amenable number.

421806856417 is a deficient number, since it is larger than the sum of its proper divisors (1).

421806856417 is an equidigital number, since it uses as much as digits as its factorization.

421806856417 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2580480, while the sum is 52.

The spelling of 421806856417 in words is "four hundred twenty-one billion, eight hundred six million, eight hundred fifty-six thousand, four hundred seventeen".