20861971751 has 2 divisors, whose sum is σ = 20861971752. Its totient is φ = 20861971750.

The previous prime is 20861971723. The next prime is 20861971759. The reversal of 20861971751 is 15717916802.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20861971751 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20861971696 and 20861971705.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20861971759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10430985875 + 10430985876.

It is an arithmetic number, because the mean of its divisors is an integer number (10430985876).

Almost surely, 2^20861971751 is an apocalyptic number.

20861971751 is a deficient number, since it is larger than the sum of its proper divisors (1).

20861971751 is an equidigital number, since it uses as much as digits as its factorization.

20861971751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 211680, while the sum is 47.

The spelling of 20861971751 in words is "twenty billion, eight hundred sixty-one million, nine hundred seventy-one thousand, seven hundred fifty-one".