21317481 has 12 divisors (see below), whose sum is σ = 32131008. Its totient is φ = 13593624.

The previous prime is 21317479. The next prime is 21317509. The reversal of 21317481 is 18471312.

It is not a de Polignac number, because 21317481 - 2¹ = 21317479 is a prime.

It is a super-2 number, since 2×21317481² = 908869992370722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21317441) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 51285 + ... + 51698.

It is an arithmetic number, because the mean of its divisors is an integer number (2677584).

Almost surely, 2^21317481 is an apocalyptic number.

It is an amenable number.

21317481 is a deficient number, since it is larger than the sum of its proper divisors (10813527).

21317481 is a wasteful number, since it uses less digits than its factorization.

21317481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103012 (or 103009 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 21317481 is about 4617.0857691838. The cubic root of 21317481 is about 277.2757965049.

Adding to 21317481 its reverse (18471312), we get a palindrome (39788793).

The spelling of 21317481 in words is "twenty-one million, three hundred seventeen thousand, four hundred eighty-one".