21255559 has 8 divisors (see below), whose sum is σ = 24237360. Its totient is φ = 18466176.

The previous prime is 21255557. The next prime is 21255569. The reversal of 21255559 is 95555212.

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 21255559 - 2¹ = 21255557 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 (21255557) 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 7 ways as a sum of consecutive naturals, for example, 47869 + ... + 48310.

It is an arithmetic number, because the mean of its divisors is an integer number (3029670).

Almost surely, 2^21255559 is an apocalyptic number.

21255559 is a deficient number, since it is larger than the sum of its proper divisors (2981801).

21255559 is a wasteful number, since it uses less digits than its factorization.

21255559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96209.

The product of its digits is 22500, while the sum is 34.

The square root of 21255559 is about 4610.3751474256. The cubic root of 21255559 is about 277.0070636419.

The spelling of 21255559 in words is "twenty-one million, two hundred fifty-five thousand, five hundred fifty-nine".