21539870533 has 2 divisors, whose sum is σ = 21539870534. Its totient is φ = 21539870532.

The previous prime is 21539870497. The next prime is 21539870549. The reversal of 21539870533 is 33507893512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11358656929 + 10181213604 = 106577^2 + 100902^2 .

It is a cyclic number.

It is not a de Polignac number, because 21539870533 - 2³³ = 12949935941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21539870563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10769935266 + 10769935267.

It is an arithmetic number, because the mean of its divisors is an integer number (10769935267).

Almost surely, 2^21539870533 is an apocalyptic number.

It is an amenable number.

21539870533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21539870533 is an equidigital number, since it uses as much as digits as its factorization.

21539870533 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 680400, while the sum is 46.

The spelling of 21539870533 in words is "twenty-one billion, five hundred thirty-nine million, eight hundred seventy thousand, five hundred thirty-three".