20187665689 has 2 divisors, whose sum is σ = 20187665690. Its totient is φ = 20187665688.

The previous prime is 20187665683. The next prime is 20187665723. The reversal of 20187665689 is 98656678102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19914854400 + 272811289 = 141120^2 + 16517^2 .

It is a cyclic number.

It is not a de Polignac number, because 20187665689 - 2²¹ = 20185568537 is a prime.

It is a super-3 number, since 3×20187665689³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (20187665683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10093832844 + 10093832845.

It is an arithmetic number, because the mean of its divisors is an integer number (10093832845).

Almost surely, 2^20187665689 is an apocalyptic number.

It is an amenable number.

20187665689 is a deficient number, since it is larger than the sum of its proper divisors (1).

20187665689 is an equidigital number, since it uses as much as digits as its factorization.

20187665689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8709120, while the sum is 58.

The spelling of 20187665689 in words is "twenty billion, one hundred eighty-seven million, six hundred sixty-five thousand, six hundred eighty-nine".