21029 has 4 divisors (see below), whose sum is σ = 22284. Its totient is φ = 19776.

The previous prime is 21023. The next prime is 21031. The reversal of 21029 is 92012.

21029 = T₄₁ + T₄₂ + ... + T₅₇.

21029 is nontrivially palindromic in base 2 and base 16.

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 16129 + 4900 = 127^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 21029 - 2⁴ = 21013 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21029.

It is not an unprimeable number, because it can be changed into a prime (21023) 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, 602 + ... + 635.

It is an arithmetic number, because the mean of its divisors is an integer number (5571).

2²¹⁰²⁹ is an apocalyptic number.

It is an amenable number.

21029 is a deficient number, since it is larger than the sum of its proper divisors (1255).

21029 is a wasteful number, since it uses less digits than its factorization.

21029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254.

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

The square root of 21029 is about 145.0137924475. The cubic root of 21029 is about 27.6019357320.

The spelling of 21029 in words is "twenty-one thousand, twenty-nine".