20857871831 has 2 divisors, whose sum is σ = 20857871832. Its totient is φ = 20857871830.

The previous prime is 20857871819. The next prime is 20857871873. The reversal of 20857871831 is 13817875802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20857871831 - 2¹⁰ = 20857870807 is a prime.

It is a super-2 number, since 2×20857871831² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20857871831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20857871891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428935915 + 10428935916.

It is an arithmetic number, because the mean of its divisors is an integer number (10428935916).

Almost surely, 2^20857871831 is an apocalyptic number.

20857871831 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857871831 is an equidigital number, since it uses as much as digits as its factorization.

20857871831 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 752640, while the sum is 50.

The spelling of 20857871831 in words is "twenty billion, eight hundred fifty-seven million, eight hundred seventy-one thousand, eight hundred thirty-one".