20985136057 has 2 divisors, whose sum is σ = 20985136058. Its totient is φ = 20985136056.

The previous prime is 20985135961. The next prime is 20985136127. The reversal of 20985136057 is 75063158902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18164570176 + 2820565881 = 134776^2 + 53109^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20985136057 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20985135998 and 20985136016.

It is not a weakly prime, because it can be changed into another prime (20985137057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10492568028 + 10492568029.

It is an arithmetic number, because the mean of its divisors is an integer number (10492568029).

Almost surely, 2^20985136057 is an apocalyptic number.

It is an amenable number.

20985136057 is a deficient number, since it is larger than the sum of its proper divisors (1).

20985136057 is an equidigital number, since it uses as much as digits as its factorization.

20985136057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 453600, while the sum is 46.

The spelling of 20985136057 in words is "twenty billion, nine hundred eighty-five million, one hundred thirty-six thousand, fifty-seven".