21317457 has 32 divisors (see below), whose sum is σ = 33510400. Its totient is φ = 11803968.

The previous prime is 21317447. The next prime is 21317479. The reversal of 21317457 is 75471312.

It is not a de Polignac number, because 21317457 - 2⁴ = 21317441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21317437) 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 31 ways as a sum of consecutive naturals, for example, 153294 + ... + 153432.

It is an arithmetic number, because the mean of its divisors is an integer number (1047200).

Almost surely, 2^21317457 is an apocalyptic number.

It is an amenable number.

21317457 is a deficient number, since it is larger than the sum of its proper divisors (12192943).

21317457 is a wasteful number, since it uses less digits than its factorization.

21317457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325.

The product of its digits is 5880, while the sum is 30.

The square root of 21317457 is about 4617.0831701411. The cubic root of 21317457 is about 277.2756924491.

Adding to 21317457 its reverse (75471312), we get a palindrome (96788769).

The spelling of 21317457 in words is "twenty-one million, three hundred seventeen thousand, four hundred fifty-seven".