78420209 has 8 divisors (see below), whose sum is σ = 89973888. Its totient is φ = 66954240.

The previous prime is 78420203. The next prime is 78420227. The reversal of 78420209 is 90202487.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78420209 - 2²⁴ = 61642993 is a prime.

It is a super-2 number, since 2×78420209² = 12299458359207362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78420203) 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 in 7 ways as a sum of consecutive naturals, for example, 19997 + ... + 23594.

It is an arithmetic number, because the mean of its divisors is an integer number (11246736).

Almost surely, 2^78420209 is an apocalyptic number.

It is an amenable number.

78420209 is a deficient number, since it is larger than the sum of its proper divisors (11553679).

78420209 is a wasteful number, since it uses less digits than its factorization.

78420209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43855.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 78420209 is about 8855.5185618912. The cubic root of 78420209 is about 428.0317635174.

The spelling of 78420209 in words is "seventy-eight million, four hundred twenty thousand, two hundred nine".