21228533 has 2 divisors, whose sum is σ = 21228534. Its totient is φ = 21228532.

The previous prime is 21228509. The next prime is 21228553. The reversal of 21228533 is 33582212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12974404 + 8254129 = 3602^2 + 2873^2 .

It is a cyclic number.

It is not a de Polignac number, because 21228533 - 2⁶ = 21228469 is a prime.

It is a super-2 number, since 2×21228533² = 901301226664178, which contains 22 as substring.

It is a zygodrome in base 4.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21228553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10614266 + 10614267.

It is an arithmetic number, because the mean of its divisors is an integer number (10614267).

Almost surely, 2^21228533 is an apocalyptic number.

It is an amenable number.

21228533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21228533 is an equidigital number, since it uses as much as digits as its factorization.

21228533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 26.

The square root of 21228533 is about 4607.4432172301. The cubic root of 21228533 is about 276.8896109467.

The spelling of 21228533 in words is "twenty-one million, two hundred twenty-eight thousand, five hundred thirty-three".