78530209 has 2 divisors, whose sum is σ = 78530210. Its totient is φ = 78530208.

The previous prime is 78530197. The next prime is 78530213. The reversal of 78530209 is 90203587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41563809 + 36966400 = 6447^2 + 6080^2 .

It is a cyclic number.

It is not a de Polignac number, because 78530209 - 2²¹ = 76433057 is a prime.

It is not a weakly prime, because it can be changed into another prime (78530009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39265104 + 39265105.

It is an arithmetic number, because the mean of its divisors is an integer number (39265105).

Almost surely, 2^78530209 is an apocalyptic number.

It is an amenable number.

78530209 is a deficient number, since it is larger than the sum of its proper divisors (1).

78530209 is an equidigital number, since it uses as much as digits as its factorization.

78530209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 78530209 is about 8861.7272018495. The cubic root of 78530209 is about 428.2318033501.

The spelling of 78530209 in words is "seventy-eight million, five hundred thirty thousand, two hundred nine".