78374809 has 2 divisors, whose sum is σ = 78374810. Its totient is φ = 78374808.

The previous prime is 78374783. The next prime is 78374819. The reversal of 78374809 is 90847387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46621584 + 31753225 = 6828^2 + 5635^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78374809 is a prime.

It is a super-2 number, since 2×78374809² = 12285221371572962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78374819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39187404 + 39187405.

It is an arithmetic number, because the mean of its divisors is an integer number (39187405).

Almost surely, 2^78374809 is an apocalyptic number.

It is an amenable number.

78374809 is a deficient number, since it is larger than the sum of its proper divisors (1).

78374809 is an equidigital number, since it uses as much as digits as its factorization.

78374809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 338688, while the sum is 46.

The square root of 78374809 is about 8852.9548174607. The cubic root of 78374809 is about 427.9491470865.

The spelling of 78374809 in words is "seventy-eight million, three hundred seventy-four thousand, eight hundred nine".