21716885 has 4 divisors (see below), whose sum is σ = 26060268. Its totient is φ = 17373504.

The previous prime is 21716881. The next prime is 21716887. The reversal of 21716885 is 58861712.

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 9284209 + 12432676 = 3047^2 + 3526^2 .

It is a cyclic number.

It is not a de Polignac number, because 21716885 - 2² = 21716881 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 (21716881) 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, 2171684 + ... + 2171693.

It is an arithmetic number, because the mean of its divisors is an integer number (6515067).

Almost surely, 2^21716885 is an apocalyptic number.

It is an amenable number.

21716885 is a deficient number, since it is larger than the sum of its proper divisors (4343383).

21716885 is an equidigital number, since it uses as much as digits as its factorization.

21716885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4343382.

The product of its digits is 26880, while the sum is 38.

The square root of 21716885 is about 4660.1378734969. The cubic root of 21716885 is about 278.9967711586.

The spelling of 21716885 in words is "twenty-one million, seven hundred sixteen thousand, eight hundred eighty-five".