20856474281 has 2 divisors, whose sum is σ = 20856474282. Its totient is φ = 20856474280.

The previous prime is 20856474253. The next prime is 20856474319. The reversal of 20856474281 is 18247465802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17826522256 + 3029952025 = 133516^2 + 55045^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20856474281 is a prime.

It is a super-2 number, since 2×20856474281² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20856477281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428237140 + 10428237141.

It is an arithmetic number, because the mean of its divisors is an integer number (10428237141).

Almost surely, 2^20856474281 is an apocalyptic number.

It is an amenable number.

20856474281 is a deficient number, since it is larger than the sum of its proper divisors (1).

20856474281 is an equidigital number, since it uses as much as digits as its factorization.

20856474281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 860160, while the sum is 47.

The spelling of 20856474281 in words is "twenty billion, eight hundred fifty-six million, four hundred seventy-four thousand, two hundred eighty-one".