78429209 has 2 divisors, whose sum is σ = 78429210. Its totient is φ = 78429208.

The previous prime is 78429199. The next prime is 78429223. The reversal of 78429209 is 90292487.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74995600 + 3433609 = 8660^2 + 1853^2 .

It is an emirp because it is prime and its reverse (90292487) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78429209 - 2⁸ = 78428953 is a prime.

It is a super-2 number, since 2×78429209² = 12302281648731362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78429409) 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, 39214604 + 39214605.

It is an arithmetic number, because the mean of its divisors is an integer number (39214605).

Almost surely, 2^78429209 is an apocalyptic number.

It is an amenable number.

78429209 is a deficient number, since it is larger than the sum of its proper divisors (1).

78429209 is an equidigital number, since it uses as much as digits as its factorization.

78429209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 78429209 is about 8856.0267050185. The cubic root of 78429209 is about 428.0481374367.

The spelling of 78429209 in words is "seventy-eight million, four hundred twenty-nine thousand, two hundred nine".