21766489 has 4 divisors (see below), whose sum is σ = 21775824. Its totient is φ = 21757156.

The previous prime is 21766439. The next prime is 21766513. The reversal of 21766489 is 98466712.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21766489 - 2⁹ = 21765977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21766439) 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, 2154 + ... + 6940.

It is an arithmetic number, because the mean of its divisors is an integer number (5443956).

Almost surely, 2^21766489 is an apocalyptic number.

It is an amenable number.

21766489 is a deficient number, since it is larger than the sum of its proper divisors (9335).

21766489 is an equidigital number, since it uses as much as digits as its factorization.

21766489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9334.

The product of its digits is 145152, while the sum is 43.

The square root of 21766489 is about 4665.4569979799. The cubic root of 21766489 is about 279.2090304562.

The spelling of 21766489 in words is "twenty-one million, seven hundred sixty-six thousand, four hundred eighty-nine".