20689851157 has 2 divisors, whose sum is σ = 20689851158. Its totient is φ = 20689851156.

The previous prime is 20689851047. The next prime is 20689851167. The reversal of 20689851157 is 75115898602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12830319441 + 7859531716 = 113271^2 + 88654^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20689851157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20689851167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10344925578 + 10344925579.

It is an arithmetic number, because the mean of its divisors is an integer number (10344925579).

Almost surely, 2^20689851157 is an apocalyptic number.

It is an amenable number.

20689851157 is a deficient number, since it is larger than the sum of its proper divisors (1).

20689851157 is an equidigital number, since it uses as much as digits as its factorization.

20689851157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1209600, while the sum is 52.

The spelling of 20689851157 in words is "twenty billion, six hundred eighty-nine million, eight hundred fifty-one thousand, one hundred fifty-seven".