20687931893 has 2 divisors, whose sum is σ = 20687931894. Its totient is φ = 20687931892.

The previous prime is 20687931863. The next prime is 20687931917. The reversal of 20687931893 is 39813978602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20687931889 + 4 = 143833^2 + 2^2 .

It is a cyclic number.

It is not a de Polignac number, because 20687931893 - 2¹⁶ = 20687866357 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20687931863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10343965946 + 10343965947.

It is an arithmetic number, because the mean of its divisors is an integer number (10343965947).

Almost surely, 2^20687931893 is an apocalyptic number.

It is an amenable number.

20687931893 is a deficient number, since it is larger than the sum of its proper divisors (1).

20687931893 is an equidigital number, since it uses as much as digits as its factorization.

20687931893 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3919104, while the sum is 56.

The spelling of 20687931893 in words is "twenty billion, six hundred eighty-seven million, nine hundred thirty-one thousand, eight hundred ninety-three".