81471891 has 8 divisors (see below), whose sum is σ = 111565264. Its totient is φ = 52846560.

The previous prime is 81471883. The next prime is 81471893. The reversal of 81471891 is 19817418.

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

It is not a de Polignac number, because 81471891 - 2³ = 81471883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81471893) 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, 366880 + ... + 367101.

It is an arithmetic number, because the mean of its divisors is an integer number (13945658).

Almost surely, 2^81471891 is an apocalyptic number.

81471891 is a deficient number, since it is larger than the sum of its proper divisors (30093373).

81471891 is a wasteful number, since it uses less digits than its factorization.

81471891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734021.

The product of its digits is 16128, while the sum is 39.

The square root of 81471891 is about 9026.1780948528. The cubic root of 81471891 is about 433.5134725734.

The spelling of 81471891 in words is "eighty-one million, four hundred seventy-one thousand, eight hundred ninety-one".