21672289 has 4 divisors (see below), whose sum is σ = 21995824. Its totient is φ = 21348756.

The previous prime is 21672271. The next prime is 21672319. The reversal of 21672289 is 98227612.

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 21672289 - 2¹⁷ = 21541217 is a prime.

It is a super-2 number, since 2×21672289² = 939376220999042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21672239) 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, 161667 + ... + 161800.

It is an arithmetic number, because the mean of its divisors is an integer number (5498956).

Almost surely, 2^21672289 is an apocalyptic number.

It is an amenable number.

21672289 is a deficient number, since it is larger than the sum of its proper divisors (323535).

21672289 is an equidigital number, since it uses as much as digits as its factorization.

21672289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323534.

The product of its digits is 24192, while the sum is 37.

The square root of 21672289 is about 4655.3505775613. The cubic root of 21672289 is about 278.8056653830.

It can be divided in two parts, 216722 and 89, that added together give a triangular number (216811 = T₆₅₈).

The spelling of 21672289 in words is "twenty-one million, six hundred seventy-two thousand, two hundred eighty-nine".