21257641581201 has 27 divisors (see below), whose sum is σ = 31885402541083. Its totient is φ = 14171512081680.

The previous prime is 21257641581173. The next prime is 21257641581227. The reversal of 21257641581201 is 10218514675212.

The square root of 21257641581201 is 4610601.

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

21257641581201 is a `hidden beast` number, since 2 + 1 + 2 + 5 + 7 + 6 + 41 + 581 + 20 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19467076446801 + 1790565134400 = 4412151^2 + 1338120^2 .

It is a tau number, because it is divible by the number of its divisors (27).

It is not a de Polignac number, because 21257641581201 - 2²¹ = 21257639484049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21257641581301) 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, 373430221 + ... + 373487141.

Almost surely, 2^{21257641581201} is an apocalyptic number.

21257641581201 is the 4610601-st square number.

21257641581201 is the 2305301-st centered octagonal number.

It is an amenable number.

21257641581201 is a deficient number, since it is larger than the sum of its proper divisors (10627760959882).

21257641581201 is an frugal number, since it uses more digits than its factorization.

21257641581201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113866 (or 56924 counting only the distinct ones).

The product of its (nonzero) digits is 268800, while the sum is 45.

The spelling of 21257641581201 in words is "twenty-one trillion, two hundred fifty-seven billion, six hundred forty-one million, five hundred eighty-one thousand, two hundred one".