21085563 has 8 divisors (see below), whose sum is σ = 28712448. Its totient is φ = 13757864.

The previous prime is 21085543. The next prime is 21085567. The reversal of 21085563 is 36558012.

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 21085563 - 2⁵ = 21085531 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21085563.

It is not an unprimeable number, because it can be changed into a prime (21085567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74631 + ... + 74912.

It is an arithmetic number, because the mean of its divisors is an integer number (3589056).

Almost surely, 2^21085563 is an apocalyptic number.

21085563 is a deficient number, since it is larger than the sum of its proper divisors (7626885).

21085563 is a wasteful number, since it uses less digits than its factorization.

21085563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149593.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21085563 is about 4591.9018935513. The cubic root of 21085563 is about 276.2666112054.

The spelling of 21085563 in words is "twenty-one million, eighty-five thousand, five hundred sixty-three".