21227521 has 8 divisors (see below), whose sum is σ = 24362624. Its totient is φ = 18118080.

The previous prime is 21227513. The next prime is 21227527. The reversal of 21227521 is 12572212.

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 21227521 - 2³ = 21227513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21227492 and 21227501.

It is not an unprimeable number, because it can be changed into a prime (21227527) 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, 4605 + ... + 7978.

It is an arithmetic number, because the mean of its divisors is an integer number (3045328).

Almost surely, 2^21227521 is an apocalyptic number.

It is an amenable number.

21227521 is a deficient number, since it is larger than the sum of its proper divisors (3135103).

21227521 is a wasteful number, since it uses less digits than its factorization.

21227521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12831.

The product of its digits is 560, while the sum is 22.

The square root of 21227521 is about 4607.3333936237. Note that the first 4 decimals coincide. The cubic root of 21227521 is about 276.8852109451.

Adding to 21227521 its reverse (12572212), we get a palindrome (33799733).

The spelling of 21227521 in words is "twenty-one million, two hundred twenty-seven thousand, five hundred twenty-one".