8155798421 has 2 divisors, whose sum is σ = 8155798422. Its totient is φ = 8155798420.

The previous prime is 8155798363. The next prime is 8155798447. The reversal of 8155798421 is 1248975518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5548164196 + 2607634225 = 74486^2 + 51065^2 .

It is a cyclic number.

It is not a de Polignac number, because 8155798421 - 2²² = 8151604117 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 8155798421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8155798921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4077899210 + 4077899211.

It is an arithmetic number, because the mean of its divisors is an integer number (4077899211).

Almost surely, 2^8155798421 is an apocalyptic number.

It is an amenable number.

8155798421 is a deficient number, since it is larger than the sum of its proper divisors (1).

8155798421 is an equidigital number, since it uses as much as digits as its factorization.

8155798421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 806400, while the sum is 50.

The square root of 8155798421 is about 90309.4592000196. The cubic root of 8155798421 is about 2012.8998201863.

The spelling of 8155798421 in words is "eight billion, one hundred fifty-five million, seven hundred ninety-eight thousand, four hundred twenty-one".