20816569 has 2 divisors, whose sum is σ = 20816570. Its totient is φ = 20816568.

The previous prime is 20816539. The next prime is 20816597. The reversal of 20816569 is 96561802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14160169 + 6656400 = 3763^2 + 2580^2 .

It is a cyclic number.

It is not a de Polignac number, because 20816569 - 2¹³ = 20808377 is a prime.

It is a super-2 number, since 2×20816569² = 866659089863522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20816539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10408284 + 10408285.

It is an arithmetic number, because the mean of its divisors is an integer number (10408285).

Almost surely, 2^20816569 is an apocalyptic number.

It is an amenable number.

20816569 is a deficient number, since it is larger than the sum of its proper divisors (1).

20816569 is an equidigital number, since it uses as much as digits as its factorization.

20816569 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 20816569 is about 4562.5178355816. The cubic root of 20816569 is about 275.0867781233.

The spelling of 20816569 in words is "twenty million, eight hundred sixteen thousand, five hundred sixty-nine".