21000533 has 2 divisors, whose sum is σ = 21000534. Its totient is φ = 21000532.

The previous prime is 21000527. The next prime is 21000557. The reversal of 21000533 is 33500012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20448484 + 552049 = 4522^2 + 743^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000533 - 2⁴ = 21000517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500266 + 10500267.

It is an arithmetic number, because the mean of its divisors is an integer number (10500267).

Almost surely, 2^21000533 is an apocalyptic number.

It is an amenable number.

21000533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000533 is an equidigital number, since it uses as much as digits as its factorization.

21000533 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21000533 is about 4582.6338496546. The cubic root of 21000533 is about 275.8947517558.

Adding to 21000533 its reverse (33500012), we get a palindrome (54500545).

The spelling of 21000533 in words is "twenty-one million, five hundred thirty-three", and thus it is an aban number.