77715642881 has 2 divisors, whose sum is σ = 77715642882. Its totient is φ = 77715642880.

The previous prime is 77715642859. The next prime is 77715642929. The reversal of 77715642881 is 18824651777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75372211600 + 2343431281 = 274540^2 + 48409^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77715642881 is a prime.

It is a super-2 number, since 2×77715642881² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77715642811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38857821440 + 38857821441.

It is an arithmetic number, because the mean of its divisors is an integer number (38857821441).

Almost surely, 2^77715642881 is an apocalyptic number.

It is an amenable number.

77715642881 is a deficient number, since it is larger than the sum of its proper divisors (1).

77715642881 is an equidigital number, since it uses as much as digits as its factorization.

77715642881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5268480, while the sum is 56.

The spelling of 77715642881 in words is "seventy-seven billion, seven hundred fifteen million, six hundred forty-two thousand, eight hundred eighty-one".