20561407 has 2 divisors, whose sum is σ = 20561408. Its totient is φ = 20561406.

The previous prime is 20561369. The next prime is 20561413. The reversal of 20561407 is 70416502.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20561407 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20561417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10280703 + 10280704.

It is an arithmetic number, because the mean of its divisors is an integer number (10280704).

Almost surely, 2^20561407 is an apocalyptic number.

20561407 is a deficient number, since it is larger than the sum of its proper divisors (1).

20561407 is an equidigital number, since it uses as much as digits as its factorization.

20561407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 20561407 is about 4534.4687671215. The cubic root of 20561407 is about 273.9581826534.

Adding to 20561407 its reverse (70416502), we get a palindrome (90977909).

The spelling of 20561407 in words is "twenty million, five hundred sixty-one thousand, four hundred seven".