21246729 has 8 divisors (see below), whose sum is σ = 32376000. Its totient is φ = 12140976.

The previous prime is 21246721. The next prime is 21246751. The reversal of 21246729 is 92764212.

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

It is not a de Polignac number, because 21246729 - 2³ = 21246721 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21246729.

It is not an unprimeable number, because it can be changed into a prime (21246721) 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, 505854 + ... + 505895.

It is an arithmetic number, because the mean of its divisors is an integer number (4047000).

Almost surely, 2^21246729 is an apocalyptic number.

It is an amenable number.

21246729 is a deficient number, since it is larger than the sum of its proper divisors (11129271).

21246729 is a wasteful number, since it uses less digits than its factorization.

21246729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1011759.

The product of its digits is 12096, while the sum is 33.

The square root of 21246729 is about 4609.4174252285. The cubic root of 21246729 is about 276.9687001695.

The spelling of 21246729 in words is "twenty-one million, two hundred forty-six thousand, seven hundred twenty-nine".