21258889 has 4 divisors (see below), whose sum is σ = 21270400. Its totient is φ = 21247380.

The previous prime is 21258871. The next prime is 21258907. The reversal of 21258889 is 98885212.

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 an interprime number because it is at equal distance from previous prime (21258871) and next prime (21258907).

It is a cyclic number.

It is not a de Polignac number, because 21258889 - 2¹¹ = 21256841 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21258859) 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, 2289 + ... + 6910.

It is an arithmetic number, because the mean of its divisors is an integer number (5317600).

Almost surely, 2^21258889 is an apocalyptic number.

It is an amenable number.

21258889 is a deficient number, since it is larger than the sum of its proper divisors (11511).

21258889 is an equidigital number, since it uses as much as digits as its factorization.

21258889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11510.

The product of its digits is 92160, while the sum is 43.

The square root of 21258889 is about 4610.7362752602. The cubic root of 21258889 is about 277.0215286477.

The spelling of 21258889 in words is "twenty-one million, two hundred fifty-eight thousand, eight hundred eighty-nine".