21529829 has 4 divisors (see below), whose sum is σ = 21751884. Its totient is φ = 21307776.

The previous prime is 21529787. The next prime is 21529873. The reversal of 21529829 is 92892512.

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 7279204 + 14250625 = 2698^2 + 3775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21529829 - 2¹² = 21525733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21529792 and 21529801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21529129) 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, 110882 + ... + 111075.

It is an arithmetic number, because the mean of its divisors is an integer number (5437971).

Almost surely, 2^21529829 is an apocalyptic number.

It is an amenable number.

21529829 is a deficient number, since it is larger than the sum of its proper divisors (222055).

21529829 is an equidigital number, since it uses as much as digits as its factorization.

21529829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222054.

The product of its digits is 25920, while the sum is 38.

The square root of 21529829 is about 4640.0246766585. The cubic root of 21529829 is about 278.1934242119.

The spelling of 21529829 in words is "twenty-one million, five hundred twenty-nine thousand, eight hundred twenty-nine".