78269809 has 2 divisors, whose sum is σ = 78269810. Its totient is φ = 78269808.

The previous prime is 78269801. The next prime is 78269831. The reversal of 78269809 is 90896287.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78269409 + 400 = 8847^2 + 20^2 .

It is a cyclic number.

It is not a de Polignac number, because 78269809 - 2³ = 78269801 is a prime.

It is a super-2 number, since 2×78269809² = 12252326001792962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78269801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39134904 + 39134905.

It is an arithmetic number, because the mean of its divisors is an integer number (39134905).

Almost surely, 2^78269809 is an apocalyptic number.

It is an amenable number.

78269809 is a deficient number, since it is larger than the sum of its proper divisors (1).

78269809 is an equidigital number, since it uses as much as digits as its factorization.

78269809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 435456, while the sum is 49.

The square root of 78269809 is about 8847.0226065044. The cubic root of 78269809 is about 427.7579515458.

The spelling of 78269809 in words is "seventy-eight million, two hundred sixty-nine thousand, eight hundred nine".