78335561 has 2 divisors, whose sum is σ = 78335562. Its totient is φ = 78335560.

The previous prime is 78335557. The next prime is 78335563. The reversal of 78335561 is 16553387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67240000 + 11095561 = 8200^2 + 3331^2 .

It is a cyclic number.

It is not a de Polignac number, because 78335561 - 2² = 78335557 is a prime.

It is a super-2 number, since 2×78335561² = 12272920234369442, which contains 22 as substring.

Together with 78335563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78335563) 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, 39167780 + 39167781.

It is an arithmetic number, because the mean of its divisors is an integer number (39167781).

Almost surely, 2^78335561 is an apocalyptic number.

It is an amenable number.

78335561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78335561 is an equidigital number, since it uses as much as digits as its factorization.

78335561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75600, while the sum is 38.

The square root of 78335561 is about 8850.7378788438. The cubic root of 78335561 is about 427.8777000114.

The spelling of 78335561 in words is "seventy-eight million, three hundred thirty-five thousand, five hundred sixty-one".