21053611945521 has 12 divisors (see below), whose sum is σ = 30711869572020. Its totient is φ = 13896773560800.

The previous prime is 21053611945511. The next prime is 21053611945543. The reversal of 21053611945521 is 12554911635012.

21053611945521 is a `hidden beast` number, since 2 + 1 + 0 + 5 + 3 + 6 + 1 + 1 + 94 + 552 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 18430183855521 + 2623428090000 = 4293039^2 + 1619700^2 .

It is not a de Polignac number, because 21053611945521 - 2¹⁹ = 21053611421233 is a prime.

It is a super-2 number, since 2×21053611945521² (a number of 27 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21053611945511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11580643726 + ... + 11580645543.

It is an arithmetic number, because the mean of its divisors is an integer number (2559322464335).

Almost surely, 2^{21053611945521} is an apocalyptic number.

It is an amenable number.

21053611945521 is a deficient number, since it is larger than the sum of its proper divisors (9658257626499).

21053611945521 is a wasteful number, since it uses less digits than its factorization.

21053611945521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23161289376 (or 23161289373 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The spelling of 21053611945521 in words is "twenty-one trillion, fifty-three billion, six hundred eleven million, nine hundred forty-five thousand, five hundred twenty-one".