21221489 has 4 divisors (see below), whose sum is σ = 21715056. Its totient is φ = 20727924.

The previous prime is 21221471. The next prime is 21221503. The reversal of 21221489 is 98412212.

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 a de Polignac number, because none of the positive numbers 2^k-21221489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221419) 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, 246719 + ... + 246804.

It is an arithmetic number, because the mean of its divisors is an integer number (5428764).

Almost surely, 2^21221489 is an apocalyptic number.

It is an amenable number.

21221489 is a deficient number, since it is larger than the sum of its proper divisors (493567).

21221489 is an equidigital number, since it uses as much as digits as its factorization.

21221489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493566.

The product of its digits is 2304, while the sum is 29.

The square root of 21221489 is about 4606.6787385274. The cubic root of 21221489 is about 276.8589819471.

The spelling of 21221489 in words is "twenty-one million, two hundred twenty-one thousand, four hundred eighty-nine".