78390997 has 2 divisors, whose sum is σ = 78390998. Its totient is φ = 78390996.

The previous prime is 78390953. The next prime is 78391007. The reversal of 78390997 is 79909387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64545156 + 13845841 = 8034^2 + 3721^2 .

It is an emirp because it is prime and its reverse (79909387) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78390997 is a prime.

It is a super-2 number, since 2×78390997² = 12290296821308018, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78390497) 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, 39195498 + 39195499.

It is an arithmetic number, because the mean of its divisors is an integer number (39195499).

Almost surely, 2^78390997 is an apocalyptic number.

It is an amenable number.

78390997 is a deficient number, since it is larger than the sum of its proper divisors (1).

78390997 is an equidigital number, since it uses as much as digits as its factorization.

78390997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 857304, while the sum is 52.

The square root of 78390997 is about 8853.8690412723. The cubic root of 78390997 is about 427.9786087804.

The spelling of 78390997 in words is "seventy-eight million, three hundred ninety thousand, nine hundred ninety-seven".