81819871 has 8 divisors (see below), whose sum is σ = 98430080. Its totient is φ = 66440088.

The previous prime is 81819799. The next prime is 81819889. The reversal of 81819871 is 17891818.

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 81819871 - 2⁷ = 81819743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81819071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 307461 + ... + 307726.

It is an arithmetic number, because the mean of its divisors is an integer number (12303760).

Almost surely, 2^81819871 is an apocalyptic number.

81819871 is a deficient number, since it is larger than the sum of its proper divisors (16610209).

81819871 is a wasteful number, since it uses less digits than its factorization.

81819871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 615213.

The product of its digits is 32256, while the sum is 43.

The square root of 81819871 is about 9045.4337098892. The cubic root of 81819871 is about 434.1297986475.

The spelling of 81819871 in words is "eighty-one million, eight hundred nineteen thousand, eight hundred seventy-one".