21255505 has 8 divisors (see below), whose sum is σ = 25564032. Its totient is φ = 16966128.

The previous prime is 21255497. The next prime is 21255529. The reversal of 21255505 is 50555212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21255505 - 2³ = 21255497 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 21255505.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2217 + ... + 6886.

It is an arithmetic number, because the mean of its divisors is an integer number (3195504).

Almost surely, 2^21255505 is an apocalyptic number.

It is an amenable number.

21255505 is a deficient number, since it is larger than the sum of its proper divisors (4308527).

21255505 is an equidigital number, since it uses as much as digits as its factorization.

21255505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9575.

The product of its (nonzero) digits is 2500, while the sum is 25.

The square root of 21255505 is about 4610.3692910655. The cubic root of 21255505 is about 277.0068290618.

The spelling of 21255505 in words is "twenty-one million, two hundred fifty-five thousand, five hundred five".