20165326661 has 2 divisors, whose sum is σ = 20165326662. Its totient is φ = 20165326660.

The previous prime is 20165326631. The next prime is 20165326667. The reversal of 20165326661 is 16662356102.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13732324225 + 6433002436 = 117185^2 + 80206^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20165326661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20165326667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10082663330 + 10082663331.

It is an arithmetic number, because the mean of its divisors is an integer number (10082663331).

Almost surely, 2^20165326661 is an apocalyptic number.

It is an amenable number.

20165326661 is a deficient number, since it is larger than the sum of its proper divisors (1).

20165326661 is an equidigital number, since it uses as much as digits as its factorization.

20165326661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 38.

The spelling of 20165326661 in words is "twenty billion, one hundred sixty-five million, three hundred twenty-six thousand, six hundred sixty-one".