20565501 has 16 divisors (see below), whose sum is σ = 30077760. Its totient is φ = 12395520.

The previous prime is 20565463. The next prime is 20565509. The reversal of 20565501 is 10556502.

It is not a de Polignac number, because 20565501 - 2⁷ = 20565373 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20565509) 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 15 ways as a sum of consecutive naturals, for example, 4755 + ... + 7983.

It is an arithmetic number, because the mean of its divisors is an integer number (1879860).

Almost surely, 2^20565501 is an apocalyptic number.

It is an amenable number.

20565501 is a deficient number, since it is larger than the sum of its proper divisors (9512259).

20565501 is a wasteful number, since it uses less digits than its factorization.

20565501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3436.

The product of its (nonzero) digits is 1500, while the sum is 24.

The square root of 20565501 is about 4534.9201757032. The cubic root of 20565501 is about 273.9763641323.

It can be divided in two parts, 2056 and 5501, that added together give a palindrome (7557).

The spelling of 20565501 in words is "twenty million, five hundred sixty-five thousand, five hundred one".