21333729 has 4 divisors (see below), whose sum is σ = 28444976. Its totient is φ = 14222484.

The previous prime is 21333727. The next prime is 21333761. The reversal of 21333729 is 92733312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21333729 - 2¹ = 21333727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21333696 and 21333705.

It is not an unprimeable number, because it can be changed into a prime (21333727) 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 3 ways as a sum of consecutive naturals, for example, 3555619 + ... + 3555624.

It is an arithmetic number, because the mean of its divisors is an integer number (7111244).

Almost surely, 2^21333729 is an apocalyptic number.

It is an amenable number.

21333729 is a deficient number, since it is larger than the sum of its proper divisors (7111247).

21333729 is an equidigital number, since it uses as much as digits as its factorization.

21333729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7111246.

The product of its digits is 6804, while the sum is 30.

The square root of 21333729 is about 4618.8449854915. The cubic root of 21333729 is about 277.3462243543.

The spelling of 21333729 in words is "twenty-one million, three hundred thirty-three thousand, seven hundred twenty-nine".