21284469 has 6 divisors (see below), whose sum is σ = 30744246. Its totient is φ = 14189640.

The previous prime is 21284423. The next prime is 21284489. The reversal of 21284469 is 96448212.

It can be written as a sum of positive squares in only one way, i.e., 11902500 + 9381969 = 3450^2 + 3063^2 .

It is not a de Polignac number, because 21284469 - 2¹⁶ = 21218933 is a prime.

It is a super-2 number, since 2×21284469² = 906057241223922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284489) 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, 1182462 + ... + 1182479.

It is an arithmetic number, because the mean of its divisors is an integer number (5124041).

Almost surely, 2^21284469 is an apocalyptic number.

It is an amenable number.

21284469 is a deficient number, since it is larger than the sum of its proper divisors (9459777).

21284469 is a wasteful number, since it uses less digits than its factorization.

21284469 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2364947 (or 2364944 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21284469 is about 4613.5094017461. The cubic root of 21284469 is about 277.1325938813.

It can be divided in two parts, 212 and 84469, that added together give a square (84681 = 291²).

The spelling of 21284469 in words is "twenty-one million, two hundred eighty-four thousand, four hundred sixty-nine".