21542139105201 has 243 divisors, whose sum is σ = 38378885436801. Its totient is φ = 11629369065600.

The previous prime is 21542139105187. The next prime is 21542139105211. The reversal of 21542139105201 is 10250193124512.

The square root of 21542139105201 is 4641351.

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

21542139105201 is a `hidden beast` number, since 2 + 1 + 5 + 42 + 1 + 3 + 91 + 0 + 520 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 462801287025 + 21079337818176 = 680295^2 + 4591224^2 .

It is not a de Polignac number, because 21542139105201 - 2¹³ = 21542139097009 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21542139105211) by changing a digit.

It is a polite number, since it can be written in 242 ways as a sum of consecutive naturals, for example, 61725326775 + ... + 61725327123.

Almost surely, 2^{21542139105201} is an apocalyptic number.

21542139105201 is the 4641351-st square number.

21542139105201 is the 2320676-th centered octagonal number.

It is an amenable number.

21542139105201 is a deficient number, since it is larger than the sum of its proper divisors (16836746331600).

21542139105201 is a wasteful number, since it uses less digits than its factorization.

21542139105201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814 (or 407 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

Multiplying 21542139105201 by its sum of digits (36), we get a square (775517007787236 = 27848106²).

The spelling of 21542139105201 in words is "twenty-one trillion, five hundred forty-two billion, one hundred thirty-nine million, one hundred five thousand, two hundred one".