78555569 has 2 divisors, whose sum is σ = 78555570. Its totient is φ = 78555568.

The previous prime is 78555509. The next prime is 78555601. The reversal of 78555569 is 96555587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74166544 + 4389025 = 8612^2 + 2095^2 .

It is a cyclic number.

It is not a de Polignac number, because 78555569 - 2⁸ = 78555313 is a prime.

It is a super-2 number, since 2×78555569² = 12341954841827522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78555509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39277784 + 39277785.

It is an arithmetic number, because the mean of its divisors is an integer number (39277785).

Almost surely, 2^78555569 is an apocalyptic number.

It is an amenable number.

78555569 is a deficient number, since it is larger than the sum of its proper divisors (1).

78555569 is an equidigital number, since it uses as much as digits as its factorization.

78555569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1890000, while the sum is 50.

The square root of 78555569 is about 8863.1579586511. The cubic root of 78555569 is about 428.2778951232.

The spelling of 78555569 in words is "seventy-eight million, five hundred fifty-five thousand, five hundred sixty-nine".