775688981 has 2 divisors, whose sum is σ = 775688982. Its totient is φ = 775688980.

The previous prime is 775688959. The next prime is 775689001. The reversal of 775688981 is 189886577.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 699126481 + 76562500 = 26441^2 + 8750^2 .

It is a cyclic number.

It is not a de Polignac number, because 775688981 - 2¹⁸ = 775426837 is a prime.

It is a super-2 number, since 2×775688981² = 1203386790489636722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 775688981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (775684981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 387844490 + 387844491.

It is an arithmetic number, because the mean of its divisors is an integer number (387844491).

Almost surely, 2^775688981 is an apocalyptic number.

It is an amenable number.

775688981 is a deficient number, since it is larger than the sum of its proper divisors (1).

775688981 is an equidigital number, since it uses as much as digits as its factorization.

775688981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6773760, while the sum is 59.

The square root of 775688981 is about 27851.1935291829. The cubic root of 775688981 is about 918.8173923385.

The spelling of 775688981 in words is "seven hundred seventy-five million, six hundred eighty-eight thousand, nine hundred eighty-one".