21641329 has 4 divisors (see below), whose sum is σ = 21884580. Its totient is φ = 21398080.

The previous prime is 21641311. The next prime is 21641353. The reversal of 21641329 is 92314612.

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 4210704 + 17430625 = 2052^2 + 4175^2 .

It is a cyclic number.

It is not a de Polignac number, because 21641329 - 2¹¹ = 21639281 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21641297 and 21641306.

It is not an unprimeable number, because it can be changed into a prime (21641309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 121492 + ... + 121669.

It is an arithmetic number, because the mean of its divisors is an integer number (5471145).

Almost surely, 2^21641329 is an apocalyptic number.

It is an amenable number.

21641329 is a deficient number, since it is larger than the sum of its proper divisors (243251).

21641329 is an equidigital number, since it uses as much as digits as its factorization.

21641329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243250.

The product of its digits is 2592, while the sum is 28.

The square root of 21641329 is about 4652.0241830842. The cubic root of 21641329 is about 278.6728392811.

The spelling of 21641329 in words is "twenty-one million, six hundred forty-one thousand, three hundred twenty-nine".