77887561 has 2 divisors, whose sum is σ = 77887562. Its totient is φ = 77887560.

The previous prime is 77887529. The next prime is 77887571. The reversal of 77887561 is 16578877.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77440000 + 447561 = 8800^2 + 669^2 .

It is a cyclic number.

It is not a de Polignac number, because 77887561 - 2⁵ = 77887529 is a prime.

It is not a weakly prime, because it can be changed into another prime (77887501) 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, 38943780 + 38943781.

It is an arithmetic number, because the mean of its divisors is an integer number (38943781).

Almost surely, 2^77887561 is an apocalyptic number.

It is an amenable number.

77887561 is a deficient number, since it is larger than the sum of its proper divisors (1).

77887561 is an equidigital number, since it uses as much as digits as its factorization.

77887561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 658560, while the sum is 49.

The square root of 77887561 is about 8825.3929657551. The cubic root of 77887561 is about 427.0604645385.

The spelling of 77887561 in words is "seventy-seven million, eight hundred eighty-seven thousand, five hundred sixty-one".