21611489 has 4 divisors (see below), whose sum is σ = 21666324. Its totient is φ = 21556656.

The previous prime is 21611461. The next prime is 21611519. The reversal of 21611489 is 98411612.

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 7980625 + 13630864 = 2825^2 + 3692^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21611489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21611389) 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, 26822 + ... + 27615.

It is an arithmetic number, because the mean of its divisors is an integer number (5416581).

Almost surely, 2^21611489 is an apocalyptic number.

It is an amenable number.

21611489 is a deficient number, since it is larger than the sum of its proper divisors (54835).

21611489 is an equidigital number, since it uses as much as digits as its factorization.

21611489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54834.

The product of its digits is 3456, while the sum is 32.

The square root of 21611489 is about 4648.8158707353. The cubic root of 21611489 is about 278.5446983149.

The spelling of 21611489 in words is "twenty-one million, six hundred eleven thousand, four hundred eighty-nine".