78072209 has 2 divisors, whose sum is σ = 78072210. Its totient is φ = 78072208.

The previous prime is 78072187. The next prime is 78072271. The reversal of 78072209 is 90227087.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45900625 + 32171584 = 6775^2 + 5672^2 .

It is an emirp because it is prime and its reverse (90227087) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78072209 - 2⁸ = 78071953 is a prime.

It is not a weakly prime, because it can be changed into another prime (78072289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39036104 + 39036105.

It is an arithmetic number, because the mean of its divisors is an integer number (39036105).

Almost surely, 2^78072209 is an apocalyptic number.

It is an amenable number.

78072209 is a deficient number, since it is larger than the sum of its proper divisors (1).

78072209 is an equidigital number, since it uses as much as digits as its factorization.

78072209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 78072209 is about 8835.8479502536. The cubic root of 78072209 is about 427.3976755431.

The spelling of 78072209 in words is "seventy-eight million, seventy-two thousand, two hundred nine".