21551544401273 has 2 divisors, whose sum is σ = 21551544401274. Its totient is φ = 21551544401272.

The previous prime is 21551544401251. The next prime is 21551544401383. The reversal of 21551544401273 is 37210444515512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21034945713769 + 516598687504 = 4586387^2 + 718748^2 .

It is a cyclic number.

It is not a de Polignac number, because 21551544401273 - 2²⁰ = 21551543352697 is a prime.

It is not a weakly prime, because it can be changed into another prime (21551544401173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775772200636 + 10775772200637.

It is an arithmetic number, because the mean of its divisors is an integer number (10775772200637).

Almost surely, 2^{21551544401273} is an apocalyptic number.

It is an amenable number.

21551544401273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551544401273 is an equidigital number, since it uses as much as digits as its factorization.

21551544401273 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672000, while the sum is 44.

Adding to 21551544401273 its reverse (37210444515512), we get a palindrome (58761988916785).

The spelling of 21551544401273 in words is "twenty-one trillion, five hundred fifty-one billion, five hundred forty-four million, four hundred one thousand, two hundred seventy-three".