21673717 has 4 divisors (see below), whose sum is σ = 23340940. Its totient is φ = 20006496.

The previous prime is 21673711. The next prime is 21673741. The reversal of 21673717 is 71737612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2436721 + 19236996 = 1561^2 + 4386^2 .

It is a cyclic number.

It is not a de Polignac number, because 21673717 - 2¹¹ = 21671669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21673711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 833592 + ... + 833617.

It is an arithmetic number, because the mean of its divisors is an integer number (5835235).

Almost surely, 2^21673717 is an apocalyptic number.

It is an amenable number.

21673717 is a deficient number, since it is larger than the sum of its proper divisors (1667223).

21673717 is a wasteful number, since it uses less digits than its factorization.

21673717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1667222.

The product of its digits is 12348, while the sum is 34.

The square root of 21673717 is about 4655.5039469428. The cubic root of 21673717 is about 278.8117888055.

The spelling of 21673717 in words is "twenty-one million, six hundred seventy-three thousand, seven hundred seventeen".