20320355557 has 2 divisors, whose sum is σ = 20320355558. Its totient is φ = 20320355556.

The previous prime is 20320355521. The next prime is 20320355569. The reversal of 20320355557 is 75555302302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13953751876 + 6366603681 = 118126^2 + 79791^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20320355557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20320355597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10160177778 + 10160177779.

It is an arithmetic number, because the mean of its divisors is an integer number (10160177779).

Almost surely, 2^20320355557 is an apocalyptic number.

It is an amenable number.

20320355557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20320355557 is an equidigital number, since it uses as much as digits as its factorization.

20320355557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 157500, while the sum is 37.

Adding to 20320355557 its reverse (75555302302), we get a palindrome (95875657859).

The spelling of 20320355557 in words is "twenty billion, three hundred twenty million, three hundred fifty-five thousand, five hundred fifty-seven".