78758221 has 2 divisors, whose sum is σ = 78758222. Its totient is φ = 78758220.

The previous prime is 78758213. The next prime is 78758227. The reversal of 78758221 is 12285787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59521225 + 19236996 = 7715^2 + 4386^2 .

It is a cyclic number.

It is not a de Polignac number, because 78758221 - 2³ = 78758213 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 (78758227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39379110 + 39379111.

It is an arithmetic number, because the mean of its divisors is an integer number (39379111).

Almost surely, 2^78758221 is an apocalyptic number.

It is an amenable number.

78758221 is a deficient number, since it is larger than the sum of its proper divisors (1).

78758221 is an equidigital number, since it uses as much as digits as its factorization.

78758221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62720, while the sum is 40.

The square root of 78758221 is about 8874.5828634365. The cubic root of 78758221 is about 428.6458590464.

The spelling of 78758221 in words is "seventy-eight million, seven hundred fifty-eight thousand, two hundred twenty-one".