81780047 has 16 divisors (see below), whose sum is σ = 93104640. Its totient is φ = 71353728.

The previous prime is 81780031. The next prime is 81780059. The reversal of 81780047 is 74008718.

It is a cyclic number.

It is not a de Polignac number, because 81780047 - 2⁴ = 81780031 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81779989 and 81780016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81782047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12488 + ... + 17874.

It is an arithmetic number, because the mean of its divisors is an integer number (5819040).

Almost surely, 2^81780047 is an apocalyptic number.

81780047 is a deficient number, since it is larger than the sum of its proper divisors (11324593).

81780047 is a wasteful number, since it uses less digits than its factorization.

81780047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5470.

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 81780047 is about 9043.2321102579. The cubic root of 81780047 is about 434.0593528799.

The spelling of 81780047 in words is "eighty-one million, seven hundred eighty thousand, forty-seven".