21265289 has 4 divisors (see below), whose sum is σ = 21290256. Its totient is φ = 21240324.

The previous prime is 21265273. The next prime is 21265301. The reversal of 21265289 is 98256212.

It is a happy number.

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 not a de Polignac number, because 21265289 - 2⁴ = 21265273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21265219) 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, 11159 + ... + 12924.

It is an arithmetic number, because the mean of its divisors is an integer number (5322564).

Almost surely, 2^21265289 is an apocalyptic number.

It is an amenable number.

21265289 is a deficient number, since it is larger than the sum of its proper divisors (24967).

21265289 is an equidigital number, since it uses as much as digits as its factorization.

21265289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24966.

The product of its digits is 17280, while the sum is 35.

The square root of 21265289 is about 4611.4302553546. The cubic root of 21265289 is about 277.0493250188.

The spelling of 21265289 in words is "twenty-one million, two hundred sixty-five thousand, two hundred eighty-nine".