21724969 has 8 divisors (see below), whose sum is σ = 24864320. Its totient is φ = 18594576.

The previous prime is 21724943. The next prime is 21724991. The reversal of 21724969 is 96942712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21724969 - 2⁷ = 21724841 is a prime.

It is a super-2 number, since 2×21724969² = 943948556101922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21724939) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4207 + ... + 7819.

It is an arithmetic number, because the mean of its divisors is an integer number (3108040).

Almost surely, 2^21724969 is an apocalyptic number.

It is an amenable number.

21724969 is a deficient number, since it is larger than the sum of its proper divisors (3139351).

21724969 is an equidigital number, since it uses as much as digits as its factorization.

21724969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4479.

The product of its digits is 54432, while the sum is 40.

The square root of 21724969 is about 4661.0051491068. The cubic root of 21724969 is about 279.0313852404.

The spelling of 21724969 in words is "twenty-one million, seven hundred twenty-four thousand, nine hundred sixty-nine".