20865109 has 2 divisors, whose sum is σ = 20865110. Its totient is φ = 20865108.

The previous prime is 20865083. The next prime is 20865113. The reversal of 20865109 is 90156802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19554084 + 1311025 = 4422^2 + 1145^2 .

It is a cyclic number.

It is not a de Polignac number, because 20865109 - 2⁷ = 20864981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20865149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10432554 + 10432555.

It is an arithmetic number, because the mean of its divisors is an integer number (10432555).

Almost surely, 2^20865109 is an apocalyptic number.

It is an amenable number.

20865109 is a deficient number, since it is larger than the sum of its proper divisors (1).

20865109 is an equidigital number, since it uses as much as digits as its factorization.

20865109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 20865109 is about 4567.8341694943. The cubic root of 20865109 is about 275.3004275970.

The spelling of 20865109 in words is "twenty million, eight hundred sixty-five thousand, one hundred nine".