78818561 has 2 divisors, whose sum is σ = 78818562. Its totient is φ = 78818560.

The previous prime is 78818521. The next prime is 78818567. The reversal of 78818561 is 16581887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 75777025 + 3041536 = 8705^2 + 1744^2 .

It is a cyclic number.

It is not a de Polignac number, because 78818561 - 2⁶ = 78818497 is a prime.

It is a super-2 number, since 2×78818561² = 12424731116221442, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78818567) 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 as a sum of consecutive naturals, namely, 39409280 + 39409281.

It is an arithmetic number, because the mean of its divisors is an integer number (39409281).

Almost surely, 2^78818561 is an apocalyptic number.

It is an amenable number.

78818561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78818561 is an equidigital number, since it uses as much as digits as its factorization.

78818561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 107520, while the sum is 44.

The square root of 78818561 is about 8877.9818089473. The cubic root of 78818561 is about 428.7552990021.

The spelling of 78818561 in words is "seventy-eight million, eight hundred eighteen thousand, five hundred sixty-one".