20215565 has 8 divisors (see below), whose sum is σ = 25041408. Its totient is φ = 15650640.

The previous prime is 20215561. The next prime is 20215571. The reversal of 20215565 is 56551202.

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

It is not a de Polignac number, because 20215565 - 2² = 20215561 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 (20215561) by changing a digit.

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, 65057 + ... + 65366.

It is an arithmetic number, because the mean of its divisors is an integer number (3130176).

Almost surely, 2^20215565 is an apocalyptic number.

It is an amenable number.

20215565 is a deficient number, since it is larger than the sum of its proper divisors (4825843).

20215565 is a wasteful number, since it uses less digits than its factorization.

20215565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130459.

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 20215565 is about 4496.1722609348. The cubic root of 20215565 is about 272.4135011489.

Adding to 20215565 its reverse (56551202), we get a palindrome (76766767).

The spelling of 20215565 in words is "twenty million, two hundred fifteen thousand, five hundred sixty-five".