8172078821 has 2 divisors, whose sum is σ = 8172078822. Its totient is φ = 8172078820.

The previous prime is 8172078797. The next prime is 8172078841. The reversal of 8172078821 is 1288702718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5691042721 + 2481036100 = 75439^2 + 49810^2 .

It is a cyclic number.

It is not a de Polignac number, because 8172078821 - 2⁶ = 8172078757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8172078841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4086039410 + 4086039411.

It is an arithmetic number, because the mean of its divisors is an integer number (4086039411).

Almost surely, 2^8172078821 is an apocalyptic number.

It is an amenable number.

8172078821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8172078821 is an equidigital number, since it uses as much as digits as its factorization.

8172078821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100352, while the sum is 44.

The square root of 8172078821 is about 90399.5509999911. The cubic root of 8172078821 is about 2014.2382966610.

The spelling of 8172078821 in words is "eight billion, one hundred seventy-two million, seventy-eight thousand, eight hundred twenty-one".