21234289 has 4 divisors (see below), whose sum is σ = 21243556. Its totient is φ = 21225024.

The previous prime is 21234281. The next prime is 21234299. The reversal of 21234289 is 98243212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 230400 + 21003889 = 480^2 + 4583^2 .

It is a cyclic number.

It is not a de Polignac number, because 21234289 - 2³ = 21234281 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21234289.

It is not an unprimeable number, because it can be changed into a prime (21234281) 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, 1597 + ... + 6709.

It is an arithmetic number, because the mean of its divisors is an integer number (5310889).

Almost surely, 2^21234289 is an apocalyptic number.

It is an amenable number.

21234289 is a deficient number, since it is larger than the sum of its proper divisors (9267).

21234289 is an equidigital number, since it uses as much as digits as its factorization.

21234289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9266.

The product of its digits is 6912, while the sum is 31.

The square root of 21234289 is about 4608.0678163412. The cubic root of 21234289 is about 276.9146343837.

The spelling of 21234289 in words is "twenty-one million, two hundred thirty-four thousand, two hundred eighty-nine".