21228469 has 2 divisors, whose sum is σ = 21228470. Its totient is φ = 21228468.

The previous prime is 21228451. The next prime is 21228509. The reversal of 21228469 is 96482212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12602500 + 8625969 = 3550^2 + 2937^2 .

It is a cyclic number.

It is not a de Polignac number, because 21228469 - 2⁵ = 21228437 is a prime.

It is a super-2 number, since 2×21228469² = 901295792167922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21228409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10614234 + 10614235.

It is an arithmetic number, because the mean of its divisors is an integer number (10614235).

Almost surely, 2^21228469 is an apocalyptic number.

It is an amenable number.

21228469 is a deficient number, since it is larger than the sum of its proper divisors (1).

21228469 is an equidigital number, since it uses as much as digits as its factorization.

21228469 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 34.

The square root of 21228469 is about 4607.4362719413. The cubic root of 21228469 is about 276.8893326899.

The spelling of 21228469 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred sixty-nine".