20155041661 has 4 divisors (see below), whose sum is σ = 20172108924. Its totient is φ = 20137974400.

The previous prime is 20155041629. The next prime is 20155041667. The reversal of 20155041661 is 16614055102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16614055102 = 2 ⋅8307027551.

It can be written as a sum of positive squares in 2 ways, for example, as 16565234436 + 3589807225 = 128706^2 + 59915^2 .

It is a cyclic number.

It is not a de Polignac number, because 20155041661 - 2⁵ = 20155041629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20155041667) 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 in 3 ways as a sum of consecutive naturals, for example, 8531860 + ... + 8534221.

It is an arithmetic number, because the mean of its divisors is an integer number (5043027231).

Almost surely, 2^20155041661 is an apocalyptic number.

It is an amenable number.

20155041661 is a deficient number, since it is larger than the sum of its proper divisors (17067263).

20155041661 is a wasteful number, since it uses less digits than its factorization.

20155041661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17067262.

The product of its (nonzero) digits is 7200, while the sum is 31.

Adding to 20155041661 its reverse (16614055102), we get a palindrome (36769096763).

The spelling of 20155041661 in words is "twenty billion, one hundred fifty-five million, forty-one thousand, six hundred sixty-one".