7778135406581 has 2 divisors, whose sum is σ = 7778135406582. Its totient is φ = 7778135406580.

The previous prime is 7778135406577. The next prime is 7778135406649. The reversal of 7778135406581 is 1856045318777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4396398304081 + 3381737102500 = 2096759^2 + 1838950^2 .

It is a cyclic number.

It is not a de Polignac number, because 7778135406581 - 2² = 7778135406577 is a prime.

It is a super-2 number, since 2×7778135406581² (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 (7778135406541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3889067703290 + 3889067703291.

It is an arithmetic number, because the mean of its divisors is an integer number (3889067703291).

Almost surely, 2^{7778135406581} is an apocalyptic number.

It is an amenable number.

7778135406581 is a deficient number, since it is larger than the sum of its proper divisors (1).

7778135406581 is an equidigital number, since it uses as much as digits as its factorization.

7778135406581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39513600, while the sum is 62.

The spelling of 7778135406581 in words is "seven trillion, seven hundred seventy-eight billion, one hundred thirty-five million, four hundred six thousand, five hundred eighty-one".