776138821 has 2 divisors, whose sum is σ = 776138822. Its totient is φ = 776138820.

The previous prime is 776138761. The next prime is 776138849. The reversal of 776138821 is 128831677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 537776100 + 238362721 = 23190^2 + 15439^2 .

It is a cyclic number.

It is not a de Polignac number, because 776138821 - 2¹³ = 776130629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (776138221) 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, 388069410 + 388069411.

It is an arithmetic number, because the mean of its divisors is an integer number (388069411).

Almost surely, 2^776138821 is an apocalyptic number.

It is an amenable number.

776138821 is a deficient number, since it is larger than the sum of its proper divisors (1).

776138821 is an equidigital number, since it uses as much as digits as its factorization.

776138821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 112896, while the sum is 43.

The square root of 776138821 is about 27859.2681346801. The cubic root of 776138821 is about 918.9949725085.

The spelling of 776138821 in words is "seven hundred seventy-six million, one hundred thirty-eight thousand, eight hundred twenty-one".