21317571 has 12 divisors (see below), whose sum is σ = 33591480. Its totient is φ = 12919680.

The previous prime is 21317539. The next prime is 21317623. The reversal of 21317571 is 17571312.

It is a happy number.

It is not a de Polignac number, because 21317571 - 2⁵ = 21317539 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21317521) 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, 107566 + ... + 107763.

It is an arithmetic number, because the mean of its divisors is an integer number (2799290).

Almost surely, 2^21317571 is an apocalyptic number.

21317571 is a deficient number, since it is larger than the sum of its proper divisors (12273909).

21317571 is a wasteful number, since it uses less digits than its factorization.

21317571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215346 (or 215343 counting only the distinct ones).

The product of its digits is 1470, while the sum is 27.

The square root of 21317571 is about 4617.0955155812. The cubic root of 21317571 is about 277.2761867134.

Adding to 21317571 its reverse (17571312), we get a palindrome (38888883).

The spelling of 21317571 in words is "twenty-one million, three hundred seventeen thousand, five hundred seventy-one".