78775009 has 2 divisors, whose sum is σ = 78775010. Its totient is φ = 78775008.

The previous prime is 78774967. The next prime is 78775133. The reversal of 78775009 is 90057787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64448784 + 14326225 = 8028^2 + 3785^2 .

It is an emirp because it is prime and its reverse (90057787) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78775009 - 2⁷ = 78774881 is a prime.

It is not a weakly prime, because it can be changed into another prime (78779009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39387504 + 39387505.

It is an arithmetic number, because the mean of its divisors is an integer number (39387505).

Almost surely, 2^78775009 is an apocalyptic number.

It is an amenable number.

78775009 is a deficient number, since it is larger than the sum of its proper divisors (1).

78775009 is an equidigital number, since it uses as much as digits as its factorization.

78775009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 123480, while the sum is 43.

The square root of 78775009 is about 8875.5286603109. The cubic root of 78775009 is about 428.6763134140.

The spelling of 78775009 in words is "seventy-eight million, seven hundred seventy-five thousand, nine".