21788713 has 8 divisors (see below), whose sum is σ = 23331240. Its totient is φ = 20275200.

The previous prime is 21788681. The next prime is 21788719. The reversal of 21788713 is 31788712.

It can be written as a sum of positive squares in 4 ways, for example, as 10316944 + 11471769 = 3212^2 + 3387^2 .

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 21788713 - 2⁵ = 21788681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21788719) 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 7 ways as a sum of consecutive naturals, for example, 5688 + ... + 8713.

It is an arithmetic number, because the mean of its divisors is an integer number (2916405).

Almost surely, 2^21788713 is an apocalyptic number.

It is an amenable number.

21788713 is a deficient number, since it is larger than the sum of its proper divisors (1542527).

21788713 is a wasteful number, since it uses less digits than its factorization.

21788713 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14507.

The product of its digits is 18816, while the sum is 37.

The square root of 21788713 is about 4667.8381505789. The cubic root of 21788713 is about 279.3040240467.

Subtracting 21788713 from its reverse (31788712), we obtain a palindrome (9999999).

The spelling of 21788713 in words is "twenty-one million, seven hundred eighty-eight thousand, seven hundred thirteen".