81143947 has 2 divisors, whose sum is σ = 81143948. Its totient is φ = 81143946.

The previous prime is 81143921. The next prime is 81143963. The reversal of 81143947 is 74934118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81143947 - 2⁷ = 81143819 is a prime.

It is not a weakly prime, because it can be changed into another prime (81143987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40571973 + 40571974.

It is an arithmetic number, because the mean of its divisors is an integer number (40571974).

Almost surely, 2^81143947 is an apocalyptic number.

81143947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81143947 is an equidigital number, since it uses as much as digits as its factorization.

81143947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 37.

The square root of 81143947 is about 9007.9935057703. The cubic root of 81143947 is about 432.9310249673.

The spelling of 81143947 in words is "eighty-one million, one hundred forty-three thousand, nine hundred forty-seven".