8278642921 has 2 divisors, whose sum is σ = 8278642922. Its totient is φ = 8278642920.

The previous prime is 8278642919. The next prime is 8278643047. The reversal of 8278642921 is 1292468728.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7265175696 + 1013467225 = 85236^2 + 31835^2 .

It is a cyclic number.

It is not a de Polignac number, because 8278642921 - 2¹ = 8278642919 is a prime.

It is a super-2 number, since 2×8278642921² (a number of 21 digits) contains 22 as substring.

Together with 8278642919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (8278642901) 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, 4139321460 + 4139321461.

It is an arithmetic number, because the mean of its divisors is an integer number (4139321461).

Almost surely, 2^8278642921 is an apocalyptic number.

It is an amenable number.

8278642921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8278642921 is an equidigital number, since it uses as much as digits as its factorization.

8278642921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 774144, while the sum is 49.

The square root of 8278642921 is about 90987.0480947701. The cubic root of 8278642921 is about 2022.9557520641.

The spelling of 8278642921 in words is "eight billion, two hundred seventy-eight million, six hundred forty-two thousand, nine hundred twenty-one".