81278947 has 2 divisors, whose sum is σ = 81278948. Its totient is φ = 81278946.

The previous prime is 81278927. The next prime is 81279007. The reversal of 81278947 is 74987218.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81278947 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 81278897 and 81278906.

It is not a weakly prime, because it can be changed into another prime (81278927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40639473 + 40639474.

It is an arithmetic number, because the mean of its divisors is an integer number (40639474).

Almost surely, 2^81278947 is an apocalyptic number.

81278947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81278947 is an equidigital number, since it uses as much as digits as its factorization.

81278947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 46.

The square root of 81278947 is about 9015.4837363283. The cubic root of 81278947 is about 433.1709825087.

The spelling of 81278947 in words is "eighty-one million, two hundred seventy-eight thousand, nine hundred forty-seven".