20716609 has 2 divisors, whose sum is σ = 20716610. Its totient is φ = 20716608.

The previous prime is 20716589. The next prime is 20716627. The reversal of 20716609 is 90661702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11075584 + 9641025 = 3328^2 + 3105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20716609 - 2⁹ = 20716097 is a prime.

It is a super-3 number, since 3×20716609³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (20716639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10358304 + 10358305.

It is an arithmetic number, because the mean of its divisors is an integer number (10358305).

Almost surely, 2^20716609 is an apocalyptic number.

It is an amenable number.

20716609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20716609 is an equidigital number, since it uses as much as digits as its factorization.

20716609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 20716609 is about 4551.5501754897. The cubic root of 20716609 is about 274.6457543370.

The spelling of 20716609 in words is "twenty million, seven hundred sixteen thousand, six hundred nine".