21267521 has 8 divisors (see below), whose sum is σ = 23294304. Its totient is φ = 19256320.

The previous prime is 21267509. The next prime is 21267523. The reversal of 21267521 is 12576212.

21267521 is nontrivially palindromic in base 16.

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 21267521 - 2¹⁴ = 21251137 is a prime.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21267523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 935 + ... + 6588.

It is an arithmetic number, because the mean of its divisors is an integer number (2911788).

Almost surely, 2^21267521 is an apocalyptic number.

It is an amenable number.

21267521 is a deficient number, since it is larger than the sum of its proper divisors (2026783).

21267521 is a wasteful number, since it uses less digits than its factorization.

21267521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7791.

The product of its digits is 1680, while the sum is 26.

The square root of 21267521 is about 4611.6722563513. The cubic root of 21267521 is about 277.0590176915.

The spelling of 21267521 in words is "twenty-one million, two hundred sixty-seven thousand, five hundred twenty-one".