21716207 has 4 divisors (see below), whose sum is σ = 21778080. Its totient is φ = 21654336.

The previous prime is 21716159. The next prime is 21716237. The reversal of 21716207 is 70261712.

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

It is a cyclic number.

It is not a de Polignac number, because 21716207 - 2⁶ = 21716143 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 (21716237) 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, 30407 + ... + 31112.

It is an arithmetic number, because the mean of its divisors is an integer number (5444520).

Almost surely, 2^21716207 is an apocalyptic number.

21716207 is a deficient number, since it is larger than the sum of its proper divisors (61873).

21716207 is an equidigital number, since it uses as much as digits as its factorization.

21716207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61872.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 21716207 is about 4660.0651283002. The cubic root of 21716207 is about 278.9938677069.

Adding to 21716207 its reverse (70261712), we get a palindrome (91977919).

The spelling of 21716207 in words is "twenty-one million, seven hundred sixteen thousand, two hundred seven".