263929815081 has 27 divisors (see below), whose sum is σ = 402397485399. Its totient is φ = 166674020112.

The previous prime is 263929815047. The next prime is 263929815089. The reversal of 263929815081 is 180518929362.

The square root of 263929815081 is 513741.

It is a perfect power (a square), and thus also a powerful number.

263929815081 is a `hidden beast` number, since 2 + 6 + 39 + 29 + 81 + 508 + 1 = 666.

263929815081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 121888265625 + 142041549456 = 349125^2 + 376884^2 .

It is not a de Polignac number, because 263929815081 - 2²¹ = 263927717929 is a prime.

It is a super-4 number, since 4×263929815081⁴ (a number of 47 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (263929815089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 29278731 + ... + 29287743.

Almost surely, 2^263929815081 is an apocalyptic number.

263929815081 is the 513741-st square number.

263929815081 is the 256871-st centered octagonal number.

It is an amenable number.

263929815081 is a deficient number, since it is larger than the sum of its proper divisors (138467670318).

263929815081 is an frugal number, since it uses more digits than its factorization.

263929815081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18070 (or 9035 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The spelling of 263929815081 in words is "two hundred sixty-three billion, nine hundred twenty-nine million, eight hundred fifteen thousand, eighty-one".