78550861 has 2 divisors, whose sum is σ = 78550862. Its totient is φ = 78550860.

The previous prime is 78550783. The next prime is 78550873. The reversal of 78550861 is 16805587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47692836 + 30858025 = 6906^2 + 5555^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78550861 is a prime.

It is equal to p_4589770 and since 78550861 and 4589770 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78550961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39275430 + 39275431.

It is an arithmetic number, because the mean of its divisors is an integer number (39275431).

Almost surely, 2^78550861 is an apocalyptic number.

It is an amenable number.

78550861 is a deficient number, since it is larger than the sum of its proper divisors (1).

78550861 is an equidigital number, since it uses as much as digits as its factorization.

78550861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 78550861 is about 8862.8923608493. The cubic root of 78550861 is about 428.2693390881.

The spelling of 78550861 in words is "seventy-eight million, five hundred fifty thousand, eight hundred sixty-one".