21000029 has 4 divisors (see below), whose sum is σ = 21009276. Its totient is φ = 20990784.

The previous prime is 20999999. The next prime is 21000037. The reversal of 21000029 is 92000012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 19123129 + 1876900 = 4373^2 + 1370^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000029 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20999977 and 21000022.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000059) 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 3 ways as a sum of consecutive naturals, for example, 1397 + ... + 6629.

It is an arithmetic number, because the mean of its divisors is an integer number (5252319).

Almost surely, 2^21000029 is an apocalyptic number.

It is an amenable number.

21000029 is a deficient number, since it is larger than the sum of its proper divisors (9247).

21000029 is an equidigital number, since it uses as much as digits as its factorization.

21000029 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9246.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21000029 is about 4582.5788591142. The cubic root of 21000029 is about 275.8925446362.

The spelling of 21000029 in words is "twenty-one million, twenty-nine", and thus it is an aban number and an uban number.