21727540560961 has 25 divisors (see below), whose sum is σ = 23268713805221. Its totient is φ = 20288430648864.

The previous prime is 21727540560953. The next prime is 21727540561031. The reversal of 21727540560961 is 16906504572712.

The square root of 21727540560961 is 4661281.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6743209239361 + 14984331321600 = 2596769^2 + 3870960^2 .

It is not a de Polignac number, because 21727540560961 - 2³ = 21727540560953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21727540560161) 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 24 ways as a sum of consecutive naturals, for example, 171082996480 + ... + 171082996606.

Almost surely, 2^{21727540560961} is an apocalyptic number.

21727540560961 is the 4661281-st square number.

21727540560961 is the 2330641-st centered octagonal number.

It is an amenable number.

21727540560961 is a deficient number, since it is larger than the sum of its proper divisors (1541173244260).

21727540560961 is an frugal number, since it uses more digits than its factorization.

21727540560961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 6350400, while the sum is 55.

The spelling of 21727540560961 in words is "twenty-one trillion, seven hundred twenty-seven billion, five hundred forty million, five hundred sixty thousand, nine hundred sixty-one".