81205047 has 48 divisors (see below), whose sum is σ = 150239232. Its totient is φ = 41031360.

The previous prime is 81205037. The next prime is 81205079. The reversal of 81205047 is 74050218.

It is not a de Polignac number, because 81205047 - 2⁶ = 81204983 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81205047.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81205037) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24058 + ... + 27224.

It is an arithmetic number, because the mean of its divisors is an integer number (3129984).

Almost surely, 2^81205047 is an apocalyptic number.

81205047 is a deficient number, since it is larger than the sum of its proper divisors (69034185).

81205047 is a wasteful number, since it uses less digits than its factorization.

81205047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3228 (or 3225 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 81205047 is about 9011.3842998731. The cubic root of 81205047 is about 433.0396609163.

The spelling of 81205047 in words is "eighty-one million, two hundred five thousand, forty-seven".