20155565 has 8 divisors (see below), whose sum is σ = 24840600. Its totient is φ = 15688512.

The previous prime is 20155547. The next prime is 20155571. The reversal of 20155565 is 56555102.

It can be written as a sum of positive squares in 4 ways, for example, as 12773476 + 7382089 = 3574^2 + 2717^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20155565 - 2⁶ = 20155501 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54290 + ... + 54659.

It is an arithmetic number, because the mean of its divisors is an integer number (3105075).

Almost surely, 2^20155565 is an apocalyptic number.

It is an amenable number.

20155565 is a deficient number, since it is larger than the sum of its proper divisors (4685035).

20155565 is a wasteful number, since it uses less digits than its factorization.

20155565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108991.

The product of its (nonzero) digits is 7500, while the sum is 29.

The square root of 20155565 is about 4489.4949604605. The cubic root of 20155565 is about 272.1437254043.

The spelling of 20155565 in words is "twenty million, one hundred fifty-five thousand, five hundred sixty-five".