81131147 has 2 divisors, whose sum is σ = 81131148. Its totient is φ = 81131146.

The previous prime is 81131137. The next prime is 81131173. The reversal of 81131147 is 74113118.

It is an a-pointer prime, because the next prime (81131173) can be obtained adding 81131147 to its sum of digits (26).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81131147 - 2¹⁴ = 81114763 is a prime.

It is a Chen prime.

It is equal to p_4731740 and since 81131147 and 4731740 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81131107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40565573 + 40565574.

It is an arithmetic number, because the mean of its divisors is an integer number (40565574).

Almost surely, 2^81131147 is an apocalyptic number.

81131147 is a deficient number, since it is larger than the sum of its proper divisors (1).

81131147 is an equidigital number, since it uses as much as digits as its factorization.

81131147 is an evil number, because the sum of its binary digits is even.

The product of its digits is 672, while the sum is 26.

The square root of 81131147 is about 9007.2829976636. The cubic root of 81131147 is about 432.9082596277.

The spelling of 81131147 in words is "eighty-one million, one hundred thirty-one thousand, one hundred forty-seven".