78020221 has 2 divisors, whose sum is σ = 78020222. Its totient is φ = 78020220.

The previous prime is 78020203. The next prime is 78020233. The reversal of 78020221 is 12202087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73444900 + 4575321 = 8570^2 + 2139^2 .

It is a cyclic number.

It is not a de Polignac number, because 78020221 - 2¹³ = 78012029 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 78020192 and 78020201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78029221) 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, 39010110 + 39010111.

It is an arithmetic number, because the mean of its divisors is an integer number (39010111).

Almost surely, 2^78020221 is an apocalyptic number.

It is an amenable number.

78020221 is a deficient number, since it is larger than the sum of its proper divisors (1).

78020221 is an equidigital number, since it uses as much as digits as its factorization.

78020221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 78020221 is about 8832.9055808381. The cubic root of 78020221 is about 427.3027869588.

The spelling of 78020221 in words is "seventy-eight million, twenty thousand, two hundred twenty-one".