78399973 has 2 divisors, whose sum is σ = 78399974. Its totient is φ = 78399972.

The previous prime is 78399953. The next prime is 78399977. The reversal of 78399973 is 37999387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77141089 + 1258884 = 8783^2 + 1122^2 .

It is a cyclic number.

It is not a de Polignac number, because 78399973 - 2⁵ = 78399941 is a prime.

It is a super-2 number, since 2×78399973² = 12293111532801458, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78399977) 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, 39199986 + 39199987.

It is an arithmetic number, because the mean of its divisors is an integer number (39199987).

Almost surely, 2^78399973 is an apocalyptic number.

It is an amenable number.

78399973 is a deficient number, since it is larger than the sum of its proper divisors (1).

78399973 is an equidigital number, since it uses as much as digits as its factorization.

78399973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2571912, while the sum is 55.

The square root of 78399973 is about 8854.3759238017. The cubic root of 78399973 is about 427.9949430939.

It can be divided in two parts, 7839997 and 3, that added together give a square (7840000 = 2800²).

The spelling of 78399973 in words is "seventy-eight million, three hundred ninety-nine thousand, nine hundred seventy-three".