21265559 has 12 divisors (see below), whose sum is σ = 24874344. Its totient is φ = 18126864.

The previous prime is 21265553. The next prime is 21265577. The reversal of 21265559 is 95556212.

It is not a de Polignac number, because 21265559 - 2⁸ = 21265303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8552 + ... + 10754.

It is an arithmetic number, because the mean of its divisors is an integer number (2072862).

Almost surely, 2^21265559 is an apocalyptic number.

21265559 is a deficient number, since it is larger than the sum of its proper divisors (3608785).

21265559 is a wasteful number, since it uses less digits than its factorization.

21265559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2414 (or 2407 counting only the distinct ones).

The product of its digits is 27000, while the sum is 35.

The square root of 21265559 is about 4611.4595303439. The cubic root of 21265559 is about 277.0504975555.

The spelling of 21265559 in words is "twenty-one million, two hundred sixty-five thousand, five hundred fifty-nine".