21317427 has 6 divisors (see below), whose sum is σ = 30791852. Its totient is φ = 14211612.

The previous prime is 21317423. The next prime is 21317437. The reversal of 21317427 is 72471312.

It is a happy number.

It is not a de Polignac number, because 21317427 - 2² = 21317423 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21317427.

It is not an unprimeable number, because it can be changed into a prime (21317423) 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, 1184293 + ... + 1184310.

Almost surely, 2^21317427 is an apocalyptic number.

21317427 is a deficient number, since it is larger than the sum of its proper divisors (9474425).

21317427 is a wasteful number, since it uses less digits than its factorization.

21317427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2368609 (or 2368606 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21317427 is about 4617.0799213356. The cubic root of 21317427 is about 277.2755623793.

Adding to 21317427 its reverse (72471312), we get a palindrome (93788739).

The spelling of 21317427 in words is "twenty-one million, three hundred seventeen thousand, four hundred twenty-seven".