20896561 has 16 divisors (see below), whose sum is σ = 25574400. Its totient is φ = 16674768.

The previous prime is 20896517. The next prime is 20896567. The reversal of 20896561 is 16569802.

It is a cyclic number.

It is not a de Polignac number, because 20896561 - 2¹³ = 20888369 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20896561.

It is not an unprimeable number, because it can be changed into a prime (20896567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6516 + ... + 9178.

It is an arithmetic number, because the mean of its divisors is an integer number (1598400).

Almost surely, 2^20896561 is an apocalyptic number.

It is an amenable number.

20896561 is a deficient number, since it is larger than the sum of its proper divisors (4677839).

20896561 is a wasteful number, since it uses less digits than its factorization.

20896561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2748.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 20896561 is about 4571.2756425313. The cubic root of 20896561 is about 275.4386871506.

It can be divided in two parts, 208 and 96561, that added together give a palindrome (96769).

The spelling of 20896561 in words is "twenty million, eight hundred ninety-six thousand, five hundred sixty-one".