21500108533 has 2 divisors, whose sum is σ = 21500108534. Its totient is φ = 21500108532.

The previous prime is 21500108477. The next prime is 21500108561. The reversal of 21500108533 is 33580100512.

It is an a-pointer prime, because the next prime (21500108561) can be obtained adding 21500108533 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21038632209 + 461476324 = 145047^2 + 21482^2 .

It is a cyclic number.

It is not a de Polignac number, because 21500108533 - 2¹⁷ = 21499977461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21500138533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750054266 + 10750054267.

It is an arithmetic number, because the mean of its divisors is an integer number (10750054267).

Almost surely, 2^21500108533 is an apocalyptic number.

It is an amenable number.

21500108533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500108533 is an equidigital number, since it uses as much as digits as its factorization.

21500108533 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 28.

The spelling of 21500108533 in words is "twenty-one billion, five hundred million, one hundred eight thousand, five hundred thirty-three".