8155421 has 2 divisors, whose sum is σ = 8155422. Its totient is φ = 8155420.

The previous prime is 8155391. The next prime is 8155451. The reversal of 8155421 is 1245518.

It is a balanced prime because it is at equal distance from previous prime (8155391) and next prime (8155451).

It can be written as a sum of positive squares in only one way, i.e., 7812025 + 343396 = 2795^2 + 586^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8155421 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8155451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4077710 + 4077711.

It is an arithmetic number, because the mean of its divisors is an integer number (4077711).

Almost surely, 2^8155421 is an apocalyptic number.

It is an amenable number.

8155421 is a deficient number, since it is larger than the sum of its proper divisors (1).

8155421 is an equidigital number, since it uses as much as digits as its factorization.

8155421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1600, while the sum is 26.

The square root of 8155421 is about 2855.7697736337. The cubic root of 8155421 is about 201.2868769787.

Subtracting from 8155421 its reverse (1245518), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 8155421 in words is "eight million, one hundred fifty-five thousand, four hundred twenty-one".