21729953 has 8 divisors (see below), whose sum is σ = 24888000. Its totient is φ = 18585360.

The previous prime is 21729941. The next prime is 21729971. The reversal of 21729953 is 35992712.

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 21729953 - 2⁴ = 21729937 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21720953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 383 + ... + 6603.

It is an arithmetic number, because the mean of its divisors is an integer number (3111000).

Almost surely, 2^21729953 is an apocalyptic number.

It is an amenable number.

21729953 is a deficient number, since it is larger than the sum of its proper divisors (3158047).

21729953 is an equidigital number, since it uses as much as digits as its factorization.

21729953 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6727.

The product of its digits is 34020, while the sum is 38.

The square root of 21729953 is about 4661.5397670727. The cubic root of 21729953 is about 279.0527214594.

The spelling of 21729953 in words is "twenty-one million, seven hundred twenty-nine thousand, nine hundred fifty-three".