81000047 has 2 divisors, whose sum is σ = 81000048. Its totient is φ = 81000046.

The previous prime is 81000041. The next prime is 81000061. The reversal of 81000047 is 74000018.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81000047 - 2⁸ = 80999791 is a prime.

It is a super-2 number, since 2×81000047² = 13122015228004418, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 80999992 and 81000028.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81000041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40500023 + 40500024.

It is an arithmetic number, because the mean of its divisors is an integer number (40500024).

Almost surely, 2^81000047 is an apocalyptic number.

81000047 is a deficient number, since it is larger than the sum of its proper divisors (1).

81000047 is an equidigital number, since it uses as much as digits as its factorization.

81000047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 81000047 is about 9000.0026111107. The cubic root of 81000047 is about 432.6749547783.

The spelling of 81000047 in words is "eighty-one million, forty-seven", and thus it is an aban number and an uban number.