78582221 has 2 divisors, whose sum is σ = 78582222. Its totient is φ = 78582220.

The previous prime is 78582209. The next prime is 78582247. The reversal of 78582221 is 12228587.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74822500 + 3759721 = 8650^2 + 1939^2 .

It is a cyclic number.

It is not a de Polignac number, because 78582221 - 2¹⁰ = 78581197 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78584221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39291110 + 39291111.

It is an arithmetic number, because the mean of its divisors is an integer number (39291111).

Almost surely, 2^78582221 is an apocalyptic number.

It is an amenable number.

78582221 is a deficient number, since it is larger than the sum of its proper divisors (1).

78582221 is an equidigital number, since it uses as much as digits as its factorization.

78582221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17920, while the sum is 35.

The square root of 78582221 is about 8864.6613584502. The cubic root of 78582221 is about 428.3263244154.

The spelling of 78582221 in words is "seventy-eight million, five hundred eighty-two thousand, two hundred twenty-one".