19875281681 has 2 divisors, whose sum is σ = 19875281682. Its totient is φ = 19875281680.

The previous prime is 19875281677. The next prime is 19875281693. The reversal of 19875281681 is 18618257891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17891470081 + 1983811600 = 133759^2 + 44540^2 .

It is a cyclic number.

It is not a de Polignac number, because 19875281681 - 2² = 19875281677 is a prime.

It is a super-2 number, since 2×19875281681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19875286681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9937640840 + 9937640841.

It is an arithmetic number, because the mean of its divisors is an integer number (9937640841).

Almost surely, 2^19875281681 is an apocalyptic number.

It is an amenable number.

19875281681 is a deficient number, since it is larger than the sum of its proper divisors (1).

19875281681 is an equidigital number, since it uses as much as digits as its factorization.

19875281681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1935360, while the sum is 56.

The spelling of 19875281681 in words is "nineteen billion, eight hundred seventy-five million, two hundred eighty-one thousand, six hundred eighty-one".