21455265 has 32 divisors (see below), whose sum is σ = 37771776. Its totient is φ = 10333440.

The previous prime is 21455263. The next prime is 21455279. The reversal of 21455265 is 56255412.

It is not a de Polignac number, because 21455265 - 2¹ = 21455263 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21455261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7995 + ... + 10335.

It is an arithmetic number, because the mean of its divisors is an integer number (1180368).

Almost surely, 2^21455265 is an apocalyptic number.

It is an amenable number.

21455265 is a deficient number, since it is larger than the sum of its proper divisors (16316511).

21455265 is a wasteful number, since it uses less digits than its factorization.

21455265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2409.

The product of its digits is 12000, while the sum is 30.

The square root of 21455265 is about 4631.9828367558. The cubic root of 21455265 is about 277.8718980905.

The spelling of 21455265 in words is "twenty-one million, four hundred fifty-five thousand, two hundred sixty-five".