81029947 has 2 divisors, whose sum is σ = 81029948. Its totient is φ = 81029946.

The previous prime is 81029933. The next prime is 81029969. The reversal of 81029947 is 74992018.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81029947 is a prime.

It is not a weakly prime, because it can be changed into another prime (81029917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40514973 + 40514974.

It is an arithmetic number, because the mean of its divisors is an integer number (40514974).

Almost surely, 2^81029947 is an apocalyptic number.

81029947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81029947 is an equidigital number, since it uses as much as digits as its factorization.

81029947 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 81029947 is about 9001.6635684744. The cubic root of 81029947 is about 432.7281868035.

The spelling of 81029947 in words is "eighty-one million, twenty-nine thousand, nine hundred forty-seven".