21539343773 has 2 divisors, whose sum is σ = 21539343774. Its totient is φ = 21539343772.

The previous prime is 21539343767. The next prime is 21539343821. The reversal of 21539343773 is 37734393512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15426136804 + 6113206969 = 124202^2 + 78187^2 .

It is a cyclic number.

It is not a de Polignac number, because 21539343773 - 2¹⁴ = 21539327389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21539343713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10769671886 + 10769671887.

It is an arithmetic number, because the mean of its divisors is an integer number (10769671887).

Almost surely, 2^21539343773 is an apocalyptic number.

It is an amenable number.

21539343773 is a deficient number, since it is larger than the sum of its proper divisors (1).

21539343773 is an equidigital number, since it uses as much as digits as its factorization.

21539343773 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1428840, while the sum is 47.

The spelling of 21539343773 in words is "twenty-one billion, five hundred thirty-nine million, three hundred forty-three thousand, seven hundred seventy-three".