20665550361 has 4 divisors (see below), whose sum is σ = 27554067152. Its totient is φ = 13777033572.

The previous prime is 20665550359. The next prime is 20665550369. The reversal of 20665550361 is 16305556602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20665550361 - 2¹ = 20665550359 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20665550369) 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 in 3 ways as a sum of consecutive naturals, for example, 3444258391 + ... + 3444258396.

It is an arithmetic number, because the mean of its divisors is an integer number (6888516788).

Almost surely, 2^20665550361 is an apocalyptic number.

It is an amenable number.

20665550361 is a deficient number, since it is larger than the sum of its proper divisors (6888516791).

20665550361 is an equidigital number, since it uses as much as digits as its factorization.

20665550361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6888516790.

The product of its (nonzero) digits is 162000, while the sum is 39.

The spelling of 20665550361 in words is "twenty billion, six hundred sixty-five million, five hundred fifty thousand, three hundred sixty-one".