81900047 has 8 divisors (see below), whose sum is σ = 85335552. Its totient is φ = 78514200.

The previous prime is 81900023. The next prime is 81900059. The reversal of 81900047 is 74000918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81900047 - 2⁸ = 81899791 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81899992 and 81900019.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81900017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9029 + ... + 15662.

It is an arithmetic number, because the mean of its divisors is an integer number (10666944).

Almost surely, 2^81900047 is an apocalyptic number.

81900047 is a deficient number, since it is larger than the sum of its proper divisors (3435505).

81900047 is a wasteful number, since it uses less digits than its factorization.

81900047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24829.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 81900047 is about 9049.8644741234. The cubic root of 81900047 is about 434.2715548710.

The spelling of 81900047 in words is "eighty-one million, nine hundred thousand, forty-seven".