78097561 has 2 divisors, whose sum is σ = 78097562. Its totient is φ = 78097560.

The previous prime is 78097483. The next prime is 78097601. The reversal of 78097561 is 16579087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64080025 + 14017536 = 8005^2 + 3744^2 .

It is a cyclic number.

It is not a de Polignac number, because 78097561 - 2¹⁵ = 78064793 is a prime.

It is not a weakly prime, because it can be changed into another prime (78097361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39048780 + 39048781.

It is an arithmetic number, because the mean of its divisors is an integer number (39048781).

Almost surely, 2^78097561 is an apocalyptic number.

It is an amenable number.

78097561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78097561 is an equidigital number, since it uses as much as digits as its factorization.

78097561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 105840, while the sum is 43.

The square root of 78097561 is about 8837.2824442812. The cubic root of 78097561 is about 427.4439327768.

The spelling of 78097561 in words is "seventy-eight million, ninety-seven thousand, five hundred sixty-one".