21228489 has 6 divisors (see below), whose sum is σ = 30663386. Its totient is φ = 14152320.

The previous prime is 21228469. The next prime is 21228509. The reversal of 21228489 is 98482212.

It is an interprime number because it is at equal distance from previous prime (21228469) and next prime (21228509).

It can be written as a sum of positive squares in only one way, i.e., 15468489 + 5760000 = 3933^2 + 2400^2 .

It is not a de Polignac number, because 21228489 - 2⁹ = 21227977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21228409) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1179352 + ... + 1179369.

Almost surely, 2^21228489 is an apocalyptic number.

It is an amenable number.

21228489 is a deficient number, since it is larger than the sum of its proper divisors (9434897).

21228489 is a wasteful number, since it uses less digits than its factorization.

21228489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2358727 (or 2358724 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 21228489 is about 4607.4384423452. The cubic root of 21228489 is about 276.8894196452.

The spelling of 21228489 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred eighty-nine".