78399409 has 12 divisors (see below), whose sum is σ = 86567040. Its totient is φ = 70947800.

The previous prime is 78399401. The next prime is 78399437. The reversal of 78399409 is 90499387.

It is not a de Polignac number, because 78399409 - 2³ = 78399401 is a prime.

It is a super-2 number, since 2×78399409² = 12292934663098562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78399401) 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 11 ways as a sum of consecutive naturals, for example, 27564 + ... + 30274.

It is an arithmetic number, because the mean of its divisors is an integer number (7213920).

Almost surely, 2^78399409 is an apocalyptic number.

It is an amenable number.

78399409 is a deficient number, since it is larger than the sum of its proper divisors (8167631).

78399409 is a wasteful number, since it uses less digits than its factorization.

78399409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2972 (or 2961 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 49.

The square root of 78399409 is about 8854.3440750854. The cubic root of 78399409 is about 427.9939167767.

The spelling of 78399409 in words is "seventy-eight million, three hundred ninety-nine thousand, four hundred nine".