834640021 has 2 divisors, whose sum is σ = 834640022. Its totient is φ = 834640020.

The previous prime is 834639989. The next prime is 834640061. The reversal of 834640021 is 120046438.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 834632100 + 7921 = 28890^2 + 89^2 .

It is a cyclic number.

It is not a de Polignac number, because 834640021 - 2⁵ = 834639989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (834640061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 417320010 + 417320011.

It is an arithmetic number, because the mean of its divisors is an integer number (417320011).

Almost surely, 2^834640021 is an apocalyptic number.

It is an amenable number.

834640021 is a deficient number, since it is larger than the sum of its proper divisors (1).

834640021 is an equidigital number, since it uses as much as digits as its factorization.

834640021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 834640021 is about 28890.1370886329. The cubic root of 834640021 is about 941.5276280930.

Adding to 834640021 its reverse (120046438), we get a palindrome (954686459).

The spelling of 834640021 in words is "eight hundred thirty-four million, six hundred forty thousand, twenty-one".