11681281648521 has 9 divisors (see below), whose sum is σ = 16872977191629. Its totient is φ = 7787514263436.

The previous prime is 11681281648507. The next prime is 11681281648573. The reversal of 11681281648521 is 12584618218611.

The square root of 11681281648521 is 3417789.

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

11681281648521 is a `hidden beast` number, since 1 + 1 + 6 + 8 + 128 + 16 + 485 + 21 = 666.

11681281648521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 11681281648521 - 2³³ = 11672691713929 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (11681281647521) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 9683736 + ... + 10822998.

Almost surely, 2^{11681281648521} is an apocalyptic number.

11681281648521 is the 3417789-th square number.

11681281648521 is the 1708895-th centered octagonal number.

It is an amenable number.

11681281648521 is a deficient number, since it is larger than the sum of its proper divisors (5191695543108).

11681281648521 is an frugal number, since it uses more digits than its factorization.

11681281648521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2278532 (or 1139266 counting only the distinct ones).

The product of its digits is 1474560, while the sum is 54.

The spelling of 11681281648521 in words is "eleven trillion, six hundred eighty-one billion, two hundred eighty-one million, six hundred forty-eight thousand, five hundred twenty-one".