21123717 has 8 divisors (see below), whose sum is σ = 28197696. Its totient is φ = 14066112.

The previous prime is 21123709. The next prime is 21123721. The reversal of 21123717 is 71732112.

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

It is not a de Polignac number, because 21123717 - 2³ = 21123709 is a prime.

It is a super-2 number, since 2×21123717² = 892422839792178, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123757) 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, 673 + ... + 6534.

It is an arithmetic number, because the mean of its divisors is an integer number (3524712).

Almost surely, 2^21123717 is an apocalyptic number.

It is an amenable number.

21123717 is a deficient number, since it is larger than the sum of its proper divisors (7073979).

21123717 is an equidigital number, since it uses as much as digits as its factorization.

21123717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8187.

The product of its digits is 588, while the sum is 24.

The square root of 21123717 is about 4596.0545035933. The cubic root of 21123717 is about 276.4331441856.

Adding to 21123717 its reverse (71732112), we get a palindrome (92855829).

The spelling of 21123717 in words is "twenty-one million, one hundred twenty-three thousand, seven hundred seventeen".