21004559 has 8 divisors (see below), whose sum is σ = 21254160. Its totient is φ = 20756736.

The previous prime is 21004549. The next prime is 21004579. The reversal of 21004559 is 95540012.

21004559 is nontrivially palindromic in base 13.

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 21004559 - 2⁸ = 21004303 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 (21004549) 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, 55232 + ... + 55610.

It is an arithmetic number, because the mean of its divisors is an integer number (2656770).

Almost surely, 2^21004559 is an apocalyptic number.

21004559 is a deficient number, since it is larger than the sum of its proper divisors (249601).

21004559 is a wasteful number, since it uses less digits than its factorization.

21004559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 889.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21004559 is about 4583.0730956423. The cubic root of 21004559 is about 275.9123811702.

The spelling of 21004559 in words is "twenty-one million, four thousand, five hundred fifty-nine".