21075829 has 4 divisors (see below), whose sum is σ = 21645484. Its totient is φ = 20506176.

The previous prime is 21075827. The next prime is 21075833. The reversal of 21075829 is 92857012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14326225 + 6749604 = 3785^2 + 2598^2 .

It is a cyclic number.

It is not a de Polignac number, because 21075829 - 2¹ = 21075827 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21075794 and 21075803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075827) 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, 284772 + ... + 284845.

It is an arithmetic number, because the mean of its divisors is an integer number (5411371).

Almost surely, 2^21075829 is an apocalyptic number.

It is an amenable number.

21075829 is a deficient number, since it is larger than the sum of its proper divisors (569655).

21075829 is an equidigital number, since it uses as much as digits as its factorization.

21075829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 569654.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21075829 is about 4590.8418617940. The cubic root of 21075829 is about 276.2240924906.

It can be divided in two parts, 21075 and 829, that added together give a square (21904 = 148²).

The spelling of 21075829 in words is "twenty-one million, seventy-five thousand, eight hundred twenty-nine".