20865559 has 16 divisors (see below), whose sum is σ = 24837120. Its totient is φ = 17278560.

The previous prime is 20865557. The next prime is 20865583. The reversal of 20865559 is 95556802.

It is not a de Polignac number, because 20865559 - 2¹ = 20865557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20865557) 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, 10374 + ... + 12220.

It is an arithmetic number, because the mean of its divisors is an integer number (1552320).

Almost surely, 2^20865559 is an apocalyptic number.

20865559 is a deficient number, since it is larger than the sum of its proper divisors (3971561).

20865559 is a wasteful number, since it uses less digits than its factorization.

20865559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1950.

The product of its (nonzero) digits is 108000, while the sum is 40.

The square root of 20865559 is about 4567.8834267087. The cubic root of 20865559 is about 275.3024067272.

The spelling of 20865559 in words is "twenty million, eight hundred sixty-five thousand, five hundred fifty-nine".