21252559 has 4 divisors (see below), whose sum is σ = 21273616. Its totient is φ = 21231504.

The previous prime is 21252551. The next prime is 21252571. The reversal of 21252559 is 95525212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21252559 - 2³ = 21252551 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 21252559.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8934 + ... + 11059.

It is an arithmetic number, because the mean of its divisors is an integer number (5318404).

Almost surely, 2^21252559 is an apocalyptic number.

21252559 is a deficient number, since it is larger than the sum of its proper divisors (21057).

21252559 is a wasteful number, since it uses less digits than its factorization.

21252559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21056.

The product of its digits is 9000, while the sum is 31.

The square root of 21252559 is about 4610.0497828115. The cubic root of 21252559 is about 276.9940308114.

The spelling of 21252559 in words is "twenty-one million, two hundred fifty-two thousand, five hundred fifty-nine".