21010729 has 4 divisors (see below), whose sum is σ = 21098880. Its totient is φ = 20922580.

The previous prime is 21010723. The next prime is 21010733. The reversal of 21010729 is 92701012.

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 a cyclic number.

It is not a de Polignac number, because 21010729 - 2³ = 21010721 is a prime.

It is a super-2 number, since 2×21010729² = 882901466222882, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43717 + ... + 44194.

It is an arithmetic number, because the mean of its divisors is an integer number (5274720).

Almost surely, 2^21010729 is an apocalyptic number.

It is an amenable number.

21010729 is a deficient number, since it is larger than the sum of its proper divisors (88151).

21010729 is an equidigital number, since it uses as much as digits as its factorization.

21010729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88150.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21010729 is about 4583.7461753461. The cubic root of 21010729 is about 275.9393945554.

The spelling of 21010729 in words is "twenty-one million, ten thousand, seven hundred twenty-nine".