81799947 has 6 divisors (see below), whose sum is σ = 118155492. Its totient is φ = 54533292.

The previous prime is 81799897. The next prime is 81799973. The reversal of 81799947 is 74999718.

It is not a de Polignac number, because 81799947 - 2¹² = 81795851 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81799893 and 81799902.

It is not an unprimeable number, because it can be changed into a prime (81799987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4544433 + ... + 4544450.

It is an arithmetic number, because the mean of its divisors is an integer number (19692582).

Almost surely, 2^81799947 is an apocalyptic number.

81799947 is a deficient number, since it is larger than the sum of its proper divisors (36355545).

81799947 is a wasteful number, since it uses less digits than its factorization.

81799947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9088889 (or 9088886 counting only the distinct ones).

The product of its digits is 1143072, while the sum is 54.

The square root of 81799947 is about 9044.3323136647. The cubic root of 81799947 is about 434.0945573946.

The spelling of 81799947 in words is "eighty-one million, seven hundred ninety-nine thousand, nine hundred forty-seven".