21113717 has 8 divisors (see below), whose sum is σ = 21984216. Its totient is φ = 20259072.

The previous prime is 21113707. The next prime is 21113723. The reversal of 21113717 is 71731112.

It can be written as a sum of positive squares in 4 ways, for example, as 1674436 + 19439281 = 1294^2 + 4409^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21113717 - 2¹⁸ = 20851573 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21113692 and 21113701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1208 + ... + 6609.

It is an arithmetic number, because the mean of its divisors is an integer number (2748027).

Almost surely, 2^21113717 is an apocalyptic number.

It is an amenable number.

21113717 is a deficient number, since it is larger than the sum of its proper divisors (870499).

21113717 is an equidigital number, since it uses as much as digits as its factorization.

21113717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7927.

The product of its digits is 294, while the sum is 23.

The square root of 21113717 is about 4594.9664851879. The cubic root of 21113717 is about 276.3895160089.

Adding to 21113717 its reverse (71731112), we get a palindrome (92844829).

The spelling of 21113717 in words is "twenty-one million, one hundred thirteen thousand, seven hundred seventeen".