21284533 has 2 divisors, whose sum is σ = 21284534. Its totient is φ = 21284532.

The previous prime is 21284519. The next prime is 21284551. The reversal of 21284533 is 33548212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17114769 + 4169764 = 4137^2 + 2042^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21284533 is a prime.

It is equal to p_1346815 and since 21284533 and 1346815 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 (21284933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10642266 + 10642267.

It is an arithmetic number, because the mean of its divisors is an integer number (10642267).

Almost surely, 2^21284533 is an apocalyptic number.

It is an amenable number.

21284533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21284533 is an equidigital number, since it uses as much as digits as its factorization.

21284533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 28.

The square root of 21284533 is about 4613.5163378924. The cubic root of 21284533 is about 277.1328716498.

It can be divided in two parts, 212845 and 33, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 21284533 in words is "twenty-one million, two hundred eighty-four thousand, five hundred thirty-three".