21271563 has 6 divisors (see below), whose sum is σ = 30725604. Its totient is φ = 14181036.

The previous prime is 21271553. The next prime is 21271567. The reversal of 21271563 is 36517212.

It is a happy number.

It is not a de Polignac number, because 21271563 - 2⁶ = 21271499 is a prime.

It is a super-3 number, since 3×21271563³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21271567) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1181745 + ... + 1181762.

It is an arithmetic number, because the mean of its divisors is an integer number (5120934).

Almost surely, 2^21271563 is an apocalyptic number.

21271563 is a deficient number, since it is larger than the sum of its proper divisors (9454041).

21271563 is a wasteful number, since it uses less digits than its factorization.

21271563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2363513 (or 2363510 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21271563 is about 4612.1104713569. The cubic root of 21271563 is about 277.0765687358.

Adding to 21271563 its reverse (36517212), we get a palindrome (57788775).

The spelling of 21271563 in words is "twenty-one million, two hundred seventy-one thousand, five hundred sixty-three".