11621560539681 has 27 divisors (see below), whose sum is σ = 16818237896499. Its totient is φ = 7733177693712.

The previous prime is 11621560539671. The next prime is 11621560539727. The reversal of 11621560539681 is 18693506512611.

It is a happy number.

The square root of 11621560539681 is 3409041.

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

11621560539681 is a `hidden beast` number, since 1 + 1 + 6 + 21 + 5 + 6 + 0 + 539 + 6 + 81 = 666.

It can be written as a sum of positive squares in only one way, i.e., 5434302283281 + 6187258256400 = 2331159^2 + 2487420^2 .

It is not a de Polignac number, because 11621560539681 - 2²⁹ = 11621023668769 is a prime.

It is a super-4 number, since 4×11621560539681⁴ (a number of 53 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (11621560539671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 10871431215 + ... + 10871432283.

Almost surely, 2^{11621560539681} is an apocalyptic number.

11621560539681 is the 3409041-st square number.

11621560539681 is the 1704521-st centered octagonal number.

It is an amenable number.

11621560539681 is a deficient number, since it is larger than the sum of its proper divisors (5196677356818).

11621560539681 is an frugal number, since it uses more digits than its factorization.

11621560539681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4270 (or 2135 counting only the distinct ones).

The product of its (nonzero) digits is 2332800, while the sum is 54.

The spelling of 11621560539681 in words is "eleven trillion, six hundred twenty-one billion, five hundred sixty million, five hundred thirty-nine thousand, six hundred eighty-one".