838421809 has 2 divisors, whose sum is σ = 838421810. Its totient is φ = 838421808.

The previous prime is 838421807. The next prime is 838421851. The reversal of 838421809 is 908124838.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 681471025 + 156950784 = 26105^2 + 12528^2 .

It is a cyclic number.

It is not a de Polignac number, because 838421809 - 2¹ = 838421807 is a prime.

It is a super-2 number, since 2×838421809² = 1405902259613664962, which contains 22 as substring.

Together with 838421807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (838421803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 419210904 + 419210905.

It is an arithmetic number, because the mean of its divisors is an integer number (419210905).

Almost surely, 2^838421809 is an apocalyptic number.

It is an amenable number.

838421809 is a deficient number, since it is larger than the sum of its proper divisors (1).

838421809 is an equidigital number, since it uses as much as digits as its factorization.

838421809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 110592, while the sum is 43.

The square root of 838421809 is about 28955.5143107492. The cubic root of 838421809 is about 942.9475190895.

The spelling of 838421809 in words is "eight hundred thirty-eight million, four hundred twenty-one thousand, eight hundred nine".