78399818 has 64 divisors (see below), whose sum is σ = 151683840. Its totient is φ = 29611008.

The previous prime is 78399817. The next prime is 78399851. The reversal of 78399818 is 81899387.

It is a super-2 number, since 2×78399818² = 12293062924866248, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 78399818.

It is not an unprimeable number, because it can be changed into a prime (78399817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 255221 + ... + 255527.

It is an arithmetic number, because the mean of its divisors is an integer number (2370060).

Almost surely, 2^78399818 is an apocalyptic number.

78399818 is a deficient number, since it is larger than the sum of its proper divisors (73284022).

78399818 is a wasteful number, since it uses less digits than its factorization.

78399818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399.

The product of its digits is 870912, while the sum is 53.

The square root of 78399818 is about 8854.3671710631. The cubic root of 78399818 is about 427.9946610392.

The spelling of 78399818 in words is "seventy-eight million, three hundred ninety-nine thousand, eight hundred eighteen".