20806565737 has 2 divisors, whose sum is σ = 20806565738. Its totient is φ = 20806565736.

The previous prime is 20806565723. The next prime is 20806565743. The reversal of 20806565737 is 73756560802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13350415936 + 7456149801 = 115544^2 + 86349^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20806565737 is a prime.

It is not a weakly prime, because it can be changed into another prime (20806560737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403282868 + 10403282869.

It is an arithmetic number, because the mean of its divisors is an integer number (10403282869).

Almost surely, 2^20806565737 is an apocalyptic number.

It is an amenable number.

20806565737 is a deficient number, since it is larger than the sum of its proper divisors (1).

20806565737 is an equidigital number, since it uses as much as digits as its factorization.

20806565737 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2116800, while the sum is 49.

The spelling of 20806565737 in words is "twenty billion, eight hundred six million, five hundred sixty-five thousand, seven hundred thirty-seven".