21672329 has 4 divisors (see below), whose sum is σ = 24768384. Its totient is φ = 18576276.

The previous prime is 21672323. The next prime is 21672337. The reversal of 21672329 is 92327612.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21672329 - 2⁸ = 21672073 is a prime.

It is an alternating number because its digits alternate between even and odd.

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 = 21672295 and 21672304.

It is not an unprimeable number, because it can be changed into a prime (21672323) 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, 1548017 + ... + 1548030.

It is an arithmetic number, because the mean of its divisors is an integer number (6192096).

Almost surely, 2^21672329 is an apocalyptic number.

It is an amenable number.

21672329 is a deficient number, since it is larger than the sum of its proper divisors (3096055).

21672329 is an equidigital number, since it uses as much as digits as its factorization.

21672329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3096054.

The product of its digits is 9072, while the sum is 32.

The square root of 21672329 is about 4655.3548736912. The cubic root of 21672329 is about 278.8058369111.

The spelling of 21672329 in words is "twenty-one million, six hundred seventy-two thousand, three hundred twenty-nine".