77908823981 has 2 divisors, whose sum is σ = 77908823982. Its totient is φ = 77908823980.

The previous prime is 77908823963. The next prime is 77908824013. The reversal of 77908823981 is 18932880977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50521552900 + 27387271081 = 224770^2 + 165491^2 .

It is a cyclic number.

It is not a de Polignac number, because 77908823981 - 2¹⁴ = 77908807597 is a prime.

It is a super-2 number, since 2×77908823981² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77908823911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38954411990 + 38954411991.

It is an arithmetic number, because the mean of its divisors is an integer number (38954411991).

Almost surely, 2^77908823981 is an apocalyptic number.

It is an amenable number.

77908823981 is a deficient number, since it is larger than the sum of its proper divisors (1).

77908823981 is an equidigital number, since it uses as much as digits as its factorization.

77908823981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12192768, while the sum is 62.

The spelling of 77908823981 in words is "seventy-seven billion, nine hundred eight million, eight hundred twenty-three thousand, nine hundred eighty-one".