81431871 has 8 divisors (see below), whose sum is σ = 110886144. Its totient is φ = 53132760.

The previous prime is 81431851. The next prime is 81431879. The reversal of 81431871 is 17813418.

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

It is not a de Polignac number, because 81431871 - 2⁵ = 81431839 is a prime.

It is a super-2 number, since 2×81431871² = 13262299229121282, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81431879) 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, 288625 + ... + 288906.

It is an arithmetic number, because the mean of its divisors is an integer number (13860768).

Almost surely, 2^81431871 is an apocalyptic number.

81431871 is a deficient number, since it is larger than the sum of its proper divisors (29454273).

81431871 is a wasteful number, since it uses less digits than its factorization.

81431871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577581.

The product of its digits is 5376, while the sum is 33.

The square root of 81431871 is about 9023.9609374155. The cubic root of 81431871 is about 433.4424785555.

The spelling of 81431871 in words is "eighty-one million, four hundred thirty-one thousand, eight hundred seventy-one".