21723969 has 8 divisors (see below), whose sum is σ = 28989792. Its totient is φ = 14470400.

The previous prime is 21723959. The next prime is 21723971. The reversal of 21723969 is 96932712.

21723969 is nontrivially palindromic in base 16.

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

It is a cyclic number.

It is not a de Polignac number, because 21723969 - 2¹³ = 21715777 is a prime.

It is a super-2 number, since 2×21723969² = 943861658225922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21723959) 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 7 ways as a sum of consecutive naturals, for example, 2542 + ... + 7064.

It is an arithmetic number, because the mean of its divisors is an integer number (3623724).

Almost surely, 2^21723969 is an apocalyptic number.

It is an amenable number.

21723969 is a deficient number, since it is larger than the sum of its proper divisors (7265823).

21723969 is a wasteful number, since it uses less digits than its factorization.

21723969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6127.

The product of its digits is 40824, while the sum is 39.

The square root of 21723969 is about 4660.8978748735. The cubic root of 21723969 is about 279.0271039045.

The spelling of 21723969 in words is "twenty-one million, seven hundred twenty-three thousand, nine hundred sixty-nine".