20647565 has 16 divisors (see below), whose sum is σ = 25850880. Its totient is φ = 15812160.

The previous prime is 20647553. The next prime is 20647567. The reversal of 20647565 is 56574602.

It is not a de Polignac number, because 20647565 - 2⁸ = 20647309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20647567) 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 15 ways as a sum of consecutive naturals, for example, 18452 + ... + 19538.

It is an arithmetic number, because the mean of its divisors is an integer number (1615680).

Almost surely, 2^20647565 is an apocalyptic number.

It is an amenable number.

20647565 is a deficient number, since it is larger than the sum of its proper divisors (5203315).

20647565 is a wasteful number, since it uses less digits than its factorization.

20647565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1252.

The product of its (nonzero) digits is 50400, while the sum is 35.

The square root of 20647565 is about 4543.9591767532. The cubic root of 20647565 is about 274.3403030171.

It can be divided in two parts, 20647 and 565, that added together give a palindrome (21212).

The spelling of 20647565 in words is "twenty million, six hundred forty-seven thousand, five hundred sixty-five".