21081330456481 has 27 divisors (see below), whose sum is σ = 22393554390963. Its totient is φ = 19844942632560.

The previous prime is 21081330456443. The next prime is 21081330456491. The reversal of 21081330456481 is 18465403318012.

The square root of 21081330456481 is 4591441.

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

It can be written as a sum of positive squares in only one way, i.e., 18863863995025 + 2217466461456 = 4343255^2 + 1489116^2 .

It is not a de Polignac number, because 21081330456481 - 2¹⁹ = 21081329932193 is a prime.

It is a super-2 number, since 2×21081330456481² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21081330456491) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 5266380826 + ... + 5266384828.

It is an arithmetic number, because the mean of its divisors is an integer number (829390903369).

Almost surely, 2^{21081330456481} is an apocalyptic number.

21081330456481 is the 4591441-st square number.

21081330456481 is the 2295721-st centered octagonal number.

It is an amenable number.

21081330456481 is a deficient number, since it is larger than the sum of its proper divisors (1312223934482).

21081330456481 is an frugal number, since it uses more digits than its factorization.

21081330456481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8142 (or 4071 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 46.

The spelling of 21081330456481 in words is "twenty-one trillion, eighty-one billion, three hundred thirty million, four hundred fifty-six thousand, four hundred eighty-one".