21424969 has 4 divisors (see below), whose sum is σ = 21776260. Its totient is φ = 21073680.

The previous prime is 21424967. The next prime is 21424973. The reversal of 21424969 is 96942412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2064969 + 19360000 = 1437^2 + 4400^2 .

It is a cyclic number.

It is not a de Polignac number, because 21424969 - 2¹ = 21424967 is a prime.

It is a super-2 number, since 2×21424969² = 918058593301922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21424967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175554 + ... + 175675.

It is an arithmetic number, because the mean of its divisors is an integer number (5444065).

Almost surely, 2^21424969 is an apocalyptic number.

It is an amenable number.

21424969 is a deficient number, since it is larger than the sum of its proper divisors (351291).

21424969 is an equidigital number, since it uses as much as digits as its factorization.

21424969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351290.

The product of its digits is 31104, while the sum is 37.

The square root of 21424969 is about 4628.7113757503. The cubic root of 21424969 is about 277.7410464083.

The spelling of 21424969 in words is "twenty-one million, four hundred twenty-four thousand, nine hundred sixty-nine".