81000017999947 has 2 divisors, whose sum is σ = 81000017999948. Its totient is φ = 81000017999946.

The previous prime is 81000017999917. The next prime is 81000018000029. The reversal of 81000017999947 is 74999971000018.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81000017999947 is a prime.

It is a super-2 number, since 2×81000017999947² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81000017999917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40500008999973 + 40500008999974.

It is an arithmetic number, because the mean of its divisors is an integer number (40500008999974).

Almost surely, 2^{81000017999947} is an apocalyptic number.

81000017999947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81000017999947 is an equidigital number, since it uses as much as digits as its factorization.

81000017999947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10287648, while the sum is 64.

The spelling of 81000017999947 in words is "eighty-one trillion, seventeen million, nine hundred ninety-nine thousand, nine hundred forty-seven".