20153561 has 2 divisors, whose sum is σ = 20153562. Its totient is φ = 20153560.

The previous prime is 20153531. The next prime is 20153569. The reversal of 20153561 is 16535102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19193161 + 960400 = 4381^2 + 980^2 .

It is a cyclic number.

It is not a de Polignac number, because 20153561 - 2¹⁴ = 20137177 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20153569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10076780 + 10076781.

It is an arithmetic number, because the mean of its divisors is an integer number (10076781).

Almost surely, 2^20153561 is an apocalyptic number.

It is an amenable number.

20153561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20153561 is an equidigital number, since it uses as much as digits as its factorization.

20153561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 20153561 is about 4489.2717672246. The cubic root of 20153561 is about 272.1347056604.

Adding to 20153561 its reverse (16535102), we get a palindrome (36688663).

The spelling of 20153561 in words is "twenty million, one hundred fifty-three thousand, five hundred sixty-one".