21271521 has 8 divisors (see below), whose sum is σ = 28550464. Its totient is φ = 14086800.

The previous prime is 21271519. The next prime is 21271553. The reversal of 21271521 is 12517212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21271521 - 2¹ = 21271519 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21271501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23026 + ... + 23931.

It is an arithmetic number, because the mean of its divisors is an integer number (3568808).

Almost surely, 2^21271521 is an apocalyptic number.

It is an amenable number.

21271521 is a deficient number, since it is larger than the sum of its proper divisors (7278943).

21271521 is a wasteful number, since it uses less digits than its factorization.

21271521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47111.

The product of its digits is 280, while the sum is 21.

The square root of 21271521 is about 4612.1059181246. The cubic root of 21271521 is about 277.0763863762.

Adding to 21271521 its reverse (12517212), we get a palindrome (33788733).

The spelling of 21271521 in words is "twenty-one million, two hundred seventy-one thousand, five hundred twenty-one".