21717233 has 8 divisors (see below), whose sum is σ = 22055880. Its totient is φ = 21381120.

The previous prime is 21717217. The next prime is 21717253. The reversal of 21717233 is 33271712.

It can be written as a sum of positive squares in 4 ways, for example, as 667489 + 21049744 = 817^2 + 4588^2 .

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 21717233 - 2⁴ = 21717217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21717203) 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, 22913 + ... + 23841.

It is an arithmetic number, because the mean of its divisors is an integer number (2756985).

Almost surely, 2^21717233 is an apocalyptic number.

It is an amenable number.

21717233 is a deficient number, since it is larger than the sum of its proper divisors (338647).

21717233 is an equidigital number, since it uses as much as digits as its factorization.

21717233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1267.

The product of its digits is 1764, while the sum is 26.

The square root of 21717233 is about 4660.1752112984. The cubic root of 21717233 is about 278.9982614024.

Adding to 21717233 its reverse (33271712), we get a palindrome (54988945).

The spelling of 21717233 in words is "twenty-one million, seven hundred seventeen thousand, two hundred thirty-three".