7775999999981 has 2 divisors, whose sum is σ = 7775999999982. Its totient is φ = 7775999999980.

The previous prime is 7775999999959. The next prime is 7776000000007. The reversal of 7775999999981 is 1899999995777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7435078306756 + 340921693225 = 2726734^2 + 583885^2 .

It is a cyclic number.

It is not a de Polignac number, because 7775999999981 - 2¹⁰ = 7775999998957 is a prime.

It is a super-2 number, since 2×7775999999981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7775999999281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3887999999990 + 3887999999991.

It is an arithmetic number, because the mean of its divisors is an integer number (3887999999991).

Almost surely, 2^{7775999999981} is an apocalyptic number.

It is an amenable number.

7775999999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7775999999981 is an equidigital number, since it uses as much as digits as its factorization.

7775999999981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 65622334680, while the sum is 98.

The spelling of 7775999999981 in words is "seven trillion, seven hundred seventy-five billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".