20561897 has 8 divisors (see below), whose sum is σ = 21296640. Its totient is φ = 19831680.

The previous prime is 20561867. The next prime is 20561903. The reversal of 20561897 is 79816502.

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

It is a cyclic number.

It is not a de Polignac number, because 20561897 - 2⁶ = 20561833 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 20561897.

It is not an unprimeable number, because it can be changed into a prime (20561867) 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 7 ways as a sum of consecutive naturals, for example, 10004 + ... + 11882.

It is an arithmetic number, because the mean of its divisors is an integer number (2662080).

Almost surely, 2^20561897 is an apocalyptic number.

It is an amenable number.

20561897 is a deficient number, since it is larger than the sum of its proper divisors (734743).

20561897 is a wasteful number, since it uses less digits than its factorization.

20561897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2263.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 20561897 is about 4534.5227973845. The cubic root of 20561897 is about 273.9603588735.

The spelling of 20561897 in words is "twenty million, five hundred sixty-one thousand, eight hundred ninety-seven".