81793916783981 has 2 divisors, whose sum is σ = 81793916783982. Its totient is φ = 81793916783980.

The previous prime is 81793916783867. The next prime is 81793916784007. The reversal of 81793916783981 is 18938761939718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80896982775625 + 896934008356 = 8994275^2 + 947066^2 .

It is a cyclic number.

It is not a de Polignac number, because 81793916783981 - 2³⁸ = 81519038877037 is a prime.

It is a super-2 number, since 2×81793916783981² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81793916783896 and 81793916783905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81793916788981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40896958391990 + 40896958391991.

It is an arithmetic number, because the mean of its divisors is an integer number (40896958391991).

Almost surely, 2^{81793916783981} is an apocalyptic number.

It is an amenable number.

81793916783981 is a deficient number, since it is larger than the sum of its proper divisors (1).

81793916783981 is an equidigital number, since it uses as much as digits as its factorization.

81793916783981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 987614208, while the sum is 80.

The spelling of 81793916783981 in words is "eighty-one trillion, seven hundred ninety-three billion, nine hundred sixteen million, seven hundred eighty-three thousand, nine hundred eighty-one".