20813971847 has 2 divisors, whose sum is σ = 20813971848. Its totient is φ = 20813971846.

The previous prime is 20813971837. The next prime is 20813971889. The reversal of 20813971847 is 74817931802.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20813971847 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20813971795 and 20813971804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20813971837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10406985923 + 10406985924.

It is an arithmetic number, because the mean of its divisors is an integer number (10406985924).

Almost surely, 2^20813971847 is an apocalyptic number.

20813971847 is a deficient number, since it is larger than the sum of its proper divisors (1).

20813971847 is an equidigital number, since it uses as much as digits as its factorization.

20813971847 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 677376, while the sum is 50.

The spelling of 20813971847 in words is "twenty billion, eight hundred thirteen million, nine hundred seventy-one thousand, eight hundred forty-seven".