21330261 has 12 divisors (see below), whose sum is σ = 30876300. Its totient is φ = 14189760.

The previous prime is 21330259. The next prime is 21330271. The reversal of 21330261 is 16203312.

It can be written as a sum of positive squares in 2 ways, for example, as 10929636 + 10400625 = 3306^2 + 3225^2 .

It is not a de Polignac number, because 21330261 - 2¹ = 21330259 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2415 + ... + 6963.

It is an arithmetic number, because the mean of its divisors is an integer number (2573025).

Almost surely, 2^21330261 is an apocalyptic number.

It is an amenable number.

21330261 is a deficient number, since it is larger than the sum of its proper divisors (9546039).

21330261 is a wasteful number, since it uses less digits than its factorization.

21330261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5076 (or 5073 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21330261 is about 4618.4695517022. The cubic root of 21330261 is about 277.3311951201.

Adding to 21330261 its reverse (16203312), we get a palindrome (37533573).

The spelling of 21330261 in words is "twenty-one million, three hundred thirty thousand, two hundred sixty-one".