21317841 has 6 divisors (see below), whose sum is σ = 30792450. Its totient is φ = 14211888.

The previous prime is 21317833. The next prime is 21317851. The reversal of 21317841 is 14871312.

It can be written as a sum of positive squares in only one way, i.e., 16160400 + 5157441 = 4020^2 + 2271^2 .

It is not a de Polignac number, because 21317841 - 2³ = 21317833 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21317851) 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, 1184316 + ... + 1184333.

It is an arithmetic number, because the mean of its divisors is an integer number (5132075).

Almost surely, 2^21317841 is an apocalyptic number.

It is an amenable number.

21317841 is a deficient number, since it is larger than the sum of its proper divisors (9474609).

21317841 is a wasteful number, since it uses less digits than its factorization.

21317841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2368655 (or 2368652 counting only the distinct ones).

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

The square root of 21317841 is about 4617.1247546498. The cubic root of 21317841 is about 277.2773573323.

The spelling of 21317841 in words is "twenty-one million, three hundred seventeen thousand, eight hundred forty-one".