21550542543121 has 2 divisors, whose sum is σ = 21550542543122. Its totient is φ = 21550542543120.

The previous prime is 21550542543113. The next prime is 21550542543149. The reversal of 21550542543121 is 12134524505512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17594341982721 + 3956200560400 = 4194561^2 + 1989020^2 .

It is a cyclic number.

It is not a de Polignac number, because 21550542543121 - 2³ = 21550542543113 is a prime.

It is not a weakly prime, because it can be changed into another prime (21550542543151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775271271560 + 10775271271561.

It is an arithmetic number, because the mean of its divisors is an integer number (10775271271561).

Almost surely, 2^{21550542543121} is an apocalyptic number.

It is an amenable number.

21550542543121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21550542543121 is an equidigital number, since it uses as much as digits as its factorization.

21550542543121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240000, while the sum is 40.

The spelling of 21550542543121 in words is "twenty-one trillion, five hundred fifty billion, five hundred forty-two million, five hundred forty-three thousand, one hundred twenty-one".