21042533 has 2 divisors, whose sum is σ = 21042534. Its totient is φ = 21042532.

The previous prime is 21042491. The next prime is 21042551. The reversal of 21042533 is 33524012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19509889 + 1532644 = 4417^2 + 1238^2 .

It is a cyclic number.

It is not a de Polignac number, because 21042533 - 2¹⁴ = 21026149 is a prime.

It is a Chen prime.

It is equal to p_1332506 and since 21042533 and 1332506 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21042563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521266 + 10521267.

It is an arithmetic number, because the mean of its divisors is an integer number (10521267).

Almost surely, 2^21042533 is an apocalyptic number.

It is an amenable number.

21042533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042533 is an equidigital number, since it uses as much as digits as its factorization.

21042533 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21042533 is about 4587.2140782832. The cubic root of 21042533 is about 276.0785544445.

Adding to 21042533 its reverse (33524012), we get a palindrome (54566545).

The spelling of 21042533 in words is "twenty-one million, forty-two thousand, five hundred thirty-three".