8478915821 has 2 divisors, whose sum is σ = 8478915822. Its totient is φ = 8478915820.

The previous prime is 8478915793. The next prime is 8478915833. The reversal of 8478915821 is 1285198748.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7595994025 + 882921796 = 87155^2 + 29714^2 .

It is a cyclic number.

It is not a de Polignac number, because 8478915821 - 2²⁶ = 8411806957 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8478935821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4239457910 + 4239457911.

It is an arithmetic number, because the mean of its divisors is an integer number (4239457911).

Almost surely, 2^8478915821 is an apocalyptic number.

It is an amenable number.

8478915821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8478915821 is an equidigital number, since it uses as much as digits as its factorization.

8478915821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1290240, while the sum is 53.

The square root of 8478915821 is about 92081.0285618053. The cubic root of 8478915821 is about 2039.1387352592.

The spelling of 8478915821 in words is "eight billion, four hundred seventy-eight million, nine hundred fifteen thousand, eight hundred twenty-one".