21520263 has 8 divisors (see below), whose sum is σ = 28724976. Its totient is φ = 14331200.

The previous prime is 21520243. The next prime is 21520271. The reversal of 21520263 is 36202512.

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 21520263 - 2¹² = 21516167 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520243) 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 7 ways as a sum of consecutive naturals, for example, 198 + ... + 6563.

It is an arithmetic number, because the mean of its divisors is an integer number (3590622).

Almost surely, 2^21520263 is an apocalyptic number.

21520263 is a deficient number, since it is larger than the sum of its proper divisors (7204713).

21520263 is a wasteful number, since it uses less digits than its factorization.

21520263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7825.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21520263 is about 4638.9937486485. The cubic root of 21520263 is about 278.1522163830.

Adding to 21520263 its reverse (36202512), we get a palindrome (57722775).

The spelling of 21520263 in words is "twenty-one million, five hundred twenty thousand, two hundred sixty-three".