20661366157 has 2 divisors, whose sum is σ = 20661366158. Its totient is φ = 20661366156.

The previous prime is 20661366151. The next prime is 20661366179. The reversal of 20661366157 is 75166316602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12828054121 + 7833312036 = 113261^2 + 88506^2 .

It is a cyclic number.

It is not a de Polignac number, because 20661366157 - 2²⁷ = 20527148429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20661366151) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330683078 + 10330683079.

It is an arithmetic number, because the mean of its divisors is an integer number (10330683079).

Almost surely, 2^20661366157 is an apocalyptic number.

It is an amenable number.

20661366157 is a deficient number, since it is larger than the sum of its proper divisors (1).

20661366157 is an equidigital number, since it uses as much as digits as its factorization.

20661366157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 43.

The spelling of 20661366157 in words is "twenty billion, six hundred sixty-one million, three hundred sixty-six thousand, one hundred fifty-seven".