20561677589 has 2 divisors, whose sum is σ = 20561677590. Its totient is φ = 20561677588.

The previous prime is 20561677573. The next prime is 20561677657. The reversal of 20561677589 is 98577616502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20558684689 + 2992900 = 143383^2 + 1730^2 .

It is a cyclic number.

It is not a de Polignac number, because 20561677589 - 2⁴ = 20561677573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20561677559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10280838794 + 10280838795.

It is an arithmetic number, because the mean of its divisors is an integer number (10280838795).

Almost surely, 2^20561677589 is an apocalyptic number.

It is an amenable number.

20561677589 is a deficient number, since it is larger than the sum of its proper divisors (1).

20561677589 is an equidigital number, since it uses as much as digits as its factorization.

20561677589 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6350400, while the sum is 56.

The spelling of 20561677589 in words is "twenty billion, five hundred sixty-one million, six hundred seventy-seven thousand, five hundred eighty-nine".